Interventions aimed at increasing positive emotion facilitate the building of social connections. For instance, training in loving-kindness meditation \citep{Kok_2010,Kok2015,Kok2013} elicits positive emotion and this is dependent (moderated by) baseline vagal tone. Increases in positive emotion lead to subsequent increases in vagal tone, mediated by an increase in the perception of social connectedness. Higher vagal tone predicts greater social engagement at follow-up, and higher social engagement due to the intervention predicts further increases in vagal tone \citep*{Kok_2010}. These findings highlight a self-sustaining upward spiral between vagal function, emotion and social connections. Acute nasal administration of oxytocin may be another method to trigger cycles to improve health and wellbeing as it increases capacity for social engagement (Kemp et al., 2012). Conversely, decreased vagal activation results in increased sympathetic activity, associated with the fight-flight-or-freeze responses, which causes withdrawal behaviours (e.g. anxiety) not conducive with social environments (Porges, 2011)
The three major models surrounding individual behaviour change are the Health Belief Model, the Theory of Reasoned Action/Planned Behaviour (TRA/TPB) and the Trans-Theoretical Model. The Health Belief model (HBM) (Glanz, Rimer & Viswanath, 2008) proposes that a person’s willingness to change is dependent on seven factors, these being perceived susceptibility to and severity of a health behaviour, perceived benefits and barriers to changing a health behaviour, cues to action and self-efficacy regarding the change, along with overall modifying variables which refers to individual characteristics. An overarching value of ‘perceived threat’ of a behaviour is a key indicator of behavioural change in this model. In a similar manner of perceived threat dictating behaviours, the Protection Motivation Theory proposes that people protect themselves against threats based on the threat appraisal, referring to the perceived severity and probability of the occurrence, and coping appraisal, referring to efficacy and self-efficacy (Rogers, 1975). However, the evidence supporting the application of the HBM is weak and its predictive capacity is limited (Taylor et al., 2006). Despite this, methods to increase a ‘perceived threat’ of a behaviour have been useful, though it has not been related to the HBM. For example, pictorial warnings on cigarette packaging are significantly more effective than text-only warnings in increasing intentions to quit smoking (Noar et al., 2016).
The TRA (Fishbein & Ajzen, 1975) proposes that behaviour change depends on an individual’s attitude towards the behaviour, which is determined by the beliefs and evaluations about the outcome of the behaviour. Behaviour change also depends on the subjective norms about the behaviour in question, which is defined by beliefs about others’ opinions on the behaviour and motivations to comply with those opinions. A third component of the TRA is that of volitional control; the extent to which the behaviour can be applied consciously and become habitual over time. The TPB is an extension of TRA, in that it includes the aspect of perceived behavioural control, which refers to the beliefs regarding how easy or difficult it is to perform the behaviour (Ajzen, 1991). The evidence supporting the predictive performance of both TRA and TPB is stronger than that of the HBM, with TPB accounting for between 20% and 30% of the variance in adult health behaviours in the US and UK (Taylor et al., 2006). However, this is relatively low when needing to devise health behaviour interventions.
The Trans-Theoretical Model (Prochaska et al., 1992; Prochaska & Velicer, 1997) proposes behaviour change as a process of six stages; precontemplation (not intending to change), contemplation (think about change) preparation (intending to change a behaviour and begin with little steps), action (changing the behaviour), maintenance (sustaining the new behaviour), termination (when there is no temptation to reverse back to the old behaviour). In addition to these six steps, people can relapse and reverse back through the stages when they have not reached termination. The benefit of this model is that it holds the capacity to serve as a foundation for interventions aimed at both an individual and a community level (Taylor et al., 2006), however, the evidence suggests it is no more effective than alternative, rationally designed, interventions.
Overall, despite these models inadequately accounting for the impact of social, economic and/or environmental factors on health behaviours, they have been widely used and applied within health services (Taylor et al., 2006). Kelly and Barker (2016) highlight how behaviour change is not a simple choice an individual makes. They highlight the fact that just because it is common sense to adopt positive health behaviours, it doesn’t necessarily mean people will, and by providing more information that is straightforward to understand doesn’t equate to behaviour change. For this reason, we need to look beyond providing information and towards techniques that will facilitate behaviour change.
Other theories provide additional influencers in health behaviours, for example, it has been proposed that self-efficacy plays a key role in behaviour change; as a predictor, mediator or moderator, proposed in Bandura’s Social Cognitive Theory (1997). People are more likely to choose to undertake tasks which begin them on the path of behaviour change if their self-efficacy is high, whereas this is less likely when self-efficacy is low. In a similar manner, those with high self-efficacy about a task are more motivated to complete the task and continue with the behaviour for longer. The role of self-efficacy can be related back to the TPB in relation to perceived behaviour control (Ajzen, 1991), and is discussed in the TTM as playing a role in behaviour change across the stages (Prochaska et al., 1992). The four factors influencing self-efficacy are enactive attainment, vicarious experience, social persuasion and physiological factors, and targeting these to effectively increase self-efficacy can increase the likelihood of behaviour change (Ashford, Edmunds & French, 2010). Self-efficacy both directly and indirectly impacts health through decision making, including behaviours such as smoking, physical exercise, dieting, condom use, dental hygiene, seat belt use, and breast examination (Conner, 2005).
The above literature is a small focus amongst a larger area of work surrounding behaviour change. Other theories provide additional standpoints, including the Theory of Interpersonal Behaviour which highlights the importance of habit formation (Triandis, 1977; 1980), the Theory of Trying which focuses on the influencers upon the intention to try (Bagozzi, 1992), and the Self-determination Theory which focuses on innate psychological needs for competence, autonomy and relatedness (Deci & Ryan, 1985; Ryan & Deci, 2000).
By understanding the theoretical background to health behaviour change, interventions that target health behaviours can incorporate behaviour change strategies into the programme. One route through which long-term behaviour change can be achieved is by understanding past behaviour and habits. Forming positive health behaviour habits has been a focus for heath psychologists, with research published on diet (Adriaanse et al., 2010), physical activity (Rhodes & de Bruijn, 2010), alcohol consumption (Norman, 2011) and medication adherence \citep*{Bolman2011}. It is argued that a habit can be formed through repetition of a behaviour within a specific context (Lally, van Jaarsaveld, Potts & Wardle, 2010) and eventually this context will have the potential to trigger the behaviour without awareness, conscious control cognitive effort or deliberation (Bargh, 1994; Lally, van Jaarsveld, Potts, & Wardle, 2010; Wood & Neal, 2009).
When devising interventions to build habitual behaviours, it is important to consider the context in which an intervention is applied. For example, when aiming to ameliorate unhealthy behaviours, disrupting a cue exposure which triggers the behaviour could be a focus (Verplanken, Walker, Davis & Jurasek, 2008), however, there is the possibility of the behaviour returning when the necessary cue or context returns. This serves as an explanation as to why positive results from interventions may be short-lasting. Judah and colleagues (2018) aimed to investigate the formation of habits to create positive health behaviour changes. In line with the above discussion, they found that performing a behaviour in a more stable context was associated with more frequent repetition, which they attributed to context-specific cues being effective reminders. They also reported behaviour pleasure and intrinsic motivation to be two key factors in predicting whether a behaviour becomes a habit. Conversely, they found perceived utility and behaviour benefits to have no impact on habit formation, contradicting the HBM which highlights a key focus on perceived threat of behaviour to one’s health. Previous behaviours and habit formations are important factors when devising intervention strategies for individuals, as these behaviours have ingrained neural pathways that are easily activated (Gerdeman, Partridge, Lupica, & Lovinger, 2003; Smith, 2016; Yin & Knowlton, 2006). For this reason, strategies need to be employed that will both combat the old health behaviour and encourage the formation of neural pathways associated with the new health behaviour.
There are many BCTs that can be employed when providing interventions, promoting self-affirmation, through reflection upon important values, attributes or social relations, is one useful tool to facilitate behaviour change. Self-affirmation has proven to be a useful psychological technique regarding its ability to decrease defensiveness and increase receptivity to interventions across different health behaviours (Falk et al., 2015). By targeting self-affirmation, the neural processes involved in the self-related processing and value in response to an intervention can be altered (within the ventromedial prefrontal cortex), allowing the individual to understand the relevance and value in the intervention instead of viewing it as a threatening health intervention. A meta-analysis of 144 studies reported a positive impact of self-affirmation on message acceptance, intentions to change and subsequent behaviour (Epton et al., 2015). In a review of BCTs aimed to reduce sedentary behaviour, they reported the most effective techniques to be education, environmental restructuring, persuasion and training (Gardner et al., 2015). An example of environmental restructuring would be to provide sit-stand desks (Alkhajah et al., 2012). Studies that used techniques that focused on self-monitoring of behaviour, problem solving and changing the social or physical environment have shown promising results (Gardner et al., 2015). In a systematic review of behaviour change aimed at reducing obesity, mediators for longer-term weight control were autonomous motivation, self-efficacy and use of self-regulation skills (Teixeira et al., 2015). Overall, there are many BCTs that can be used in conjunction with treatment plans to potentially improve adherence to the treatment or suggested behaviour change.
However, whilst many interventions have been effective in eliciting behaviour change, these are often short-term successes (Avenell et al., 2004) and it is not feasible to upscale these interventions to access large population groups as they require a substantial amount of time and money (Forster, Veerman, Bardendregt & Vos, 2011). Nudge Theory provides a basis for an alternative intervention method to subtly alter health behaviours of those in the community. Thaler and Sunstein (2008) argue that there is a “choice architecture” which refers to all the external forces that guide people to make choices, and subtle environmental changes (nudges) can make a desired choice more likely. Bringing together libertarian paternalism (directing decision making whilst maintaining freedom of choice) and nudge theory offers an effective and feasible route to altering health behaviours among large populations. However, this method of influencing health behaviours comes with controversy, with the argument that it undermines the UK government’s aims which promote empowerment, freedom and fairness (Blumenthal-Barby & Burroughs, 2012; Goodwin, 2012). Nudging strategies target the impulsive and automatic system, guiding individuals to certain choices without conscious decision making (Gill & Boylan, 2012; Marteau, Hollands & Fletcher, 2012; Strack & Deutsch, 2015). Despite this, nudging is generally accepted by the public with few concerns (Junghans, Cheung & De Ridder, 2015; Petrescu, Hollands, Couturier & Marteau, 2016).
The evidence supporting the use of Nudge Theory with health behaviours is promising. A meta-analysis on dietary choices, including 42 studies, demonstrated that nudge interventions caused an average increase in healthier consumption decisions by 15.3% (Arno & Thomas, 2016). As a result of promising research, a project named ‘Supreme Nudge’ has been developed to target dietary and physical activity behaviour changes in low socioeconomic areas to reduce the burden of cardiometabolic health problems (Lakerveld et al., 2018). The aim of the project is to implement and evaluate the impact of environmental changes (nudges) on lifestyle behaviours and cardiometabolic health in adults. The targeted intervention will focus on food pricing, environmental nudging and tailored feedback for physical activity. The researchers have developed this project with the awareness that targeting individual-level factors, such as educational strategies, are insufficient in eliciting behaviour change, particularly for those in lower SES groups (Angermayr, Melchart & Linde, 2010). Whereas targeting the environment can prove effective in encouraging health behaviour changes. For example, adjusting the pricing on food products causes subsequent changes in food purchases (Niebylski, Redburn, Duhaney & Campbell, 2015; WHO, 2015), with discounts on fruits and vegetables increasing purchase and consumption on such items (Ball et al., 2015; Geliebter et al., 2013; Ni Mhurchu et al., 2010; Waterlander et al., 2013).
There is a need to incorporate theory-driven, behaviour change techniques (BCT) into care packages and interventions. It is not enough to simply provide the information, given that the four leading non-communicable diseases (cancer, cardiovascular disease, type 2 diabetes and respiratory disease) are mostly preventable through positive health behaviours (Marteau, Hollands & Kelly, 2015). It is argued that when devising techniques for behaviour change, a wider focus is needed that does not solely focus on the individual, but also incorporates social and economic pressures that act upon the individual (Kelly & Barker, 2016). With this is mind, theories of behaviour change and BCTs need to be a focus when targeting health behaviours, instead of simply expecting people to adhere to the treatment programme.
BCTs are particularly important for people with chronic conditions given that healthy behaviour changes after disease onset can lower the risk of recurrence, reduce symptom severity, increase functioning and extend longevity (Aldana et al., 2003; Jolliffe et al., 2001; Speck et al., 2010; Williamson et al., 2000), highlighting the importance of implementing BCTs to facilitate this is vital. In addition, data highlights that despite the diagnosis of a chronic condition, the vast majority of individuals do not adopt long-term positive health behaviours (Newsom et al., 2011). This is surprising given that theories of health behaviour would propose that a diagnosis of a health condition would present as a serious threat and at least minimally lead to an initial stage of change (Prochaska & Prochaska, 2005). However, past behaviours and habits can provide an explanation for why many people do not change to more positive health behaviours (Ajzen, 2002; Verplanken, 2006). However, health behaviour changes differ between conditions, for example, those with heart disease or stroke were more likely to abstain from smoking (Twardella et al., 2006) and increase exercise (Van Gool et al., 2007) compared with individuals with diabetes.
Research highlights that those with chronic conditions are more likely to track a health indicator or symptom and are more likely to benefit from health tracking (Fox & Duggan, 2013). If health tracking was used in conjunction with goal setting and other BCTs, this would be an efficient clinical target to improve the health of those living with chronic conditions. BCTs have proven to be effective among those living with chronic conditions, with a review of eight RCTs aimed at improving exercise adherence among individuals with persistent musculoskeletal pain (PMSK) finding social support, goal setting, instruction of behaviour, demonstration of behaviour and practise/rehearsal to be effective in improving exercise adherence (Meade et al., 2019). Popular wearable technology currently offers a number of BCTs, including goal setting, social support, social comparison, prompts/cues and rewards which can be used to facilitate behaviour change (Lyons, Lewis, Mayrsohn & Rowland, 2014).

Discussion

Wellbeing involves 'connection'... connection to ourselves, to others and to the environment. We suggest that vagal function provides a key mediator of health and wellbeing attributable to activities to promote wellbeing across these domains. There is now good evidence that vagus nerve connects us to ourselves (i.e. 80% of vagal nerve fibres are afferent nerves providing a structural link between mental and physical health, [REF]), to others (the vagus promotes social connection, [REF]), and to nature (vagal function is impacted on by a host of environmental factors). Vagal function may be considered as an index of resilience - underpinned by psychological flexibility \cite{Kashdan_2010} - an important consideration when seeking to build the health and wellbeing of individuals with or without chronic conditions. We encourage psychological scientists to draw upon a combination of strategies that involve facilitating positive psychological moments in addition to positive health behaviours, mindful of the major theoretical frameworks that have been proposed previously. To date, the discipline of positive psychology has been restricted to enhancing wellbeing by focusing on strategies to promote positive psychological moments. We argue that the impact of positive psychological interventions could be improved by integrating interventions that also focus on physical health, which we now know to have important impacts on mental - in addition to physical - health [REF]. 
With regards to the impact of community on individual health and wellbeing, it is worth considering the impacts of culture when building resilience in populations. The extent to which different cultures promote individualism (most developed nations including Australia, UK and US) versus collectivism (most developing nations, e.g. Brazil and China) will have differential impacts on resilience. Individualistic cultures characterise the individual as an active, independent agent, detached from the physical and social environment in which they live. By contrast, in collectivist cultures, the individual is seen as a responsive agent connected to the physical and social environment; wellbeing becomes less subjective and more relevant to the objective standards of others  \citep*{Ryff_2014a}. Wellbeing - and the various strategies that can employed to promote it - will therefore vary across cultures \cite{Eckersley2006}, dependent on people’s values and goals, and influenced by culture \citep*{DIENER_1997a}. Take for example, the cultural diversity in the expression of gratitude \cite{Floyd_2018}. Speakers of English and Italian are more likely to express gratitude in everyday situations than speakers of other languages including Polish and Russian. Other research has demonstrated that collectivist cultures - in this case,  the Taiwanese - do not experience changes in state gratitude, positive affect or negative affect when practising gratitude \cite{chang}, perhaps because they are fulfilling expected role obligations. Finally, it is important to note that community values and subsequent behaviours can be influenced through sociostructural factors such as governmental policies, a consideration highlighted in our original GENIAL model \cite{Kemp_2017} and a topic we discussed in section \ref{225494}.
Finally, our updated model extends beyond the individual and community, to incorporate the broader impacts of the environment. Mindful of previously proposed social ecological theories [REF] and Glenn Albrecht's work on 'Earth Emotions' \cite{albrecht2019}, we emphasise that the individual is intimately connected to the community and environment in such a way that XXX