Lifestyle physical activity such as personally powered transport (walk or cycle to work, stair climbing) is the current target of public health. Current approaches to physical activity promotion are based within a Socio-Ecological model. Such an approach recognises that the environment and policy decisions can have major impacts on physical activity, in addition to the effects of intrapersonal and interpersonal factors. This course takes an inclusive approach to the issue. Hence it outlines the energy minimisation of locomotion, the perceptual processes that govern eco-motion and the fit of this perception with the environment. Following this, the social and environmental determinants of lifestyle physical activity are outlined. Thus issues about the development of habitual behaviour, and effect of social and environmental constraints on that behaviour are covered. The course ends with a series of lectures on interventions based on social marketing and this nascent Socio-Ecological model of lifestyle physical activity.