The physical health benefits of exercise include improved glycemic control, body composition, cardiorespiratory fitness and physical functioning. Anti-depressive and anxiolytic effects of exercise have previously been established, however people with mental illness are significantly less likely to be physically active or engage in structured exercise compared to the general population. This low level of physical activity, combined with higher prevalence of smoking, contribute to an increased prevalence of metabolic syndrome and diabetes in people with mental illness. Given the potential double effect that exercise can have on both physical and mental health outcomes, lifestyle interventions incorporating dietary and exercise strategies are increasing within mental health settings. The need to balance best-practice exercise guidelines with the unique barriers facing people with a mental illness presents unique challenges in addition to those faced by the general population in relation to commencing and maintaining an exercise regime. Significant heterogeneity between existing interventions also contributes to uncertainty regarding best-practice exercise guidelines. An overview of the exercise and mental health literature will be provided including meta-analysis data evaluating the effect of interventions on anthropomorphic outcomes in people with mental illness. The importance of adequate reporting of intervention details and methodology will be discussed, and results from a recent randomised controlled trial of exercise on symptoms of depression and anthropometry in people with posttraumatic stress disorder will be presented.