In several countries, prescribed exercise is used to facilitate physical activity in a sedentary population, which is at risk of developing lifestyle diseases. Since long-term effect of prescribed exercise to some degree fails to happen when people participate in prescribed exercise interventions, it is necessary to introduce other ways of thinking. This book discusses how to enhance people's adherence to a physically active lifestyle after prescribed exercise and why it is important to incorporate a health psychological understanding of behaviour change in order to generate a better milieu for change. It is discussed that a way of improving life-long motivation for exercise and physical activity could be to develop a model for understanding of participation in exercise and physical activity that shifts the emphasis away from a focus on treatment, health and behaviour change and towards motivation, satisfaction and enjoyment.