Throughout this book we have discussed those behaviours that place the adolescent at risk of becoming ill. In our review, we covered a wide variety of different behaviours and examined the risks involved in drug and alcohol misuse, the problems associated with eating disorders, depression, suicide, and schizophrenia as well as sex and the risks of sexually transmitted diseases such as HIV. We also examined the nature of stress and the coping mechanisms that some employ to deal with stressful events. To some extent each of these issues is concerned with lifestyle, which can be defined as those behaviours that affect one’s health status (Bruhn 1988). In this chapter, we shall pay closer attention to the concept of lifestyle and discuss the importance of exercise and a healthy diet to adolescent health.