If there is one thing that policy makers at the World Health Organisation (WHO) and residents of the South African township of Langa are likely to agree on, it is that ‘just sitting’ is not good for you. The positions from which they approach this conclusion however differ profoundly. This research investigates different conceptualisations of physical activity, health, and wellbeing, and the implications of these differences for policy on the prevention of noncommunicable diseases (NCDs) in low and middle income countries, taking South Africa as a case study. With four out of five deaths from diseases such as diabetes, heart disease and stroke now occurring in low and middle income countries, prevention, of what have been termed ‘NCDs’, in these countries is rising rapidly up the global public health agenda. Physical activity is one of the four primary risk factors which have been identified as intervention targets, but there is an acknowledged paucity of research which helps us to understand how physical activity, and inactivity, are conceptualised in low and middle income country contexts. As a result the evidence base for design of physical activity policy interventions to address NCDs is also weak. The global discourse recognises the determinants of health as socially embedded, but struggles with what this means for policy on prevention. This study explores the detail of this social embeddedness by way of ethnographic research into wellbeing, health and physical activity carried out in a South African township, and juxtaposes this with conceptualisation of these same themes emerging from a review of academic and policy-oriented literature on the prevention of NCDs in low and middle income countries. The struggles of local research groups to reconcile the demands made on them from these very different worlds are explored, and strategies for addressing the specifics of NCD prevention without abstracting health from the broader context of the person or society are discussed. The research is theoretically informed by work on wellbeing in developing countries.