Subtle environmental modifications may operate to alter health behaviours at the community level,     providing 'nudges' in a desired direction and guiding individuals to certain choices without the use of conscious decision making (Gill & Boylan, 2012; Marteau, Hollands & Fletcher, 2012; Strack & Deutsch, 2015). This offers an effective and feasible route to altering health behaviours within large populations; evidenced by meta-analysis results indicating that dietary nudge interventions can increase healthier consumption decisions by 15.3% on average (Arno & Thomas, 2016). Contemporary efforts are now utilising environmental nudges to target dietary and physical activity in adults residing in low socioeconomic areas, with the hope to reduce the burden of cardiometabolic health problems (Lakerveld et al., 2018).  Patently, concerns surround the use of this tactic relating to issues of empowerment and freedom (Blumenthal-Barby & Burroughs, 2012; Goodwin, 2012) though such methods are generally well-accepted by the public (Junghans, Cheung & De Ridder, 2015; Petrescu, Hollands, Couturier & Marteau, 2016).    
Positive affect may also comprise a key to facilitating long-term adherence to positive health behaviours. In fact, a meta-analysis of 82 studies indicates that positive affective attitudes are stronger predictors of engagement (relating to physical activity in this instance) than positive cognitive attitudes or levels of self-efficacy Rhodes, Fiala, & Conner, 2009); an effect sustained relatively long-term in even individuals previously naïve to such health behaviours (Williams et al., 2008Williams, Dunsiger, Jennings, & Marcus, 2012).Integrating evidence on positive affect with that on implicit process, Cappellen et al., present the upward spiral theory of lifestyle change to address the mechanisms through which positive affect alters future health-related decision making. Here, positive affect experienced during health behaviors are considered to increase non-conscious motives for those health behaviors. This creates an implicit incentive salience and prompts everyday decisions to repeat those behaviors. In line with the broaden-and-build theory (Fredrickson), positive affect builds a suite of endogenous vantage resources over time, comprising biological resources (e.g., cardiac vagal tone) as well as cognitive (e.g., mindfulness), psychological (e.g., purpose in life), and social (e.g., positive relations with others) resources Fredrickson (2013). This further facilitates the positive affect experienced during positive health behaviors and strengthens non-conscious motives; predicting future engagement in health behaviours Rice & Fredrickson, 2017, and resulting in behavioural maintenance. Particularly, interventions aimed at increasing positive affect simultaneously facilitate the building of social connections. For instance, training in loving-kindness meditation \citep{Kok_2010,Kok2015,Kok2013} elicits positive emotion and this is 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 in turn predicts further increases in vagal tone \citep*{Kok_2010}. This reflects a self-sustaining upward spiral between vagal function, emotion and social connections.