Volume one consists of three parts. Part one is a meta-analytic review investigating the effect of various doses of physical exercise on the symptoms of depression. The quality of twelve Randomised Controlled Trials (RCTs) was assessed. Outcomes from four RCTs were included in a meta-analysis. Results indicated that higher doses of exercise were more effective than no exercise in reducing the symptoms of depression, whereas there was no difference between lower doses of exercise and no exercise. The findings are interpreted with caution and more robust research is required to investigate the relationship between exercise and depression, addressing the methodological limitations discussed in this review. Part two is an empirical study investigating the extent to which people with the symptoms of depression could generate mental imagery to increase goal attainment. Sixty five students were given the goal of increasing brisk walking over two weeks. According to randomisation participants were either asked to rehearse the goal, to form implementation intentions about the goal or to imagine themselves undertaking the goal. Brisk walking increased with no between-group differences. It was tentatively concluded that being given a goal intention was sufficient to improve attainment. Further research, controlling for research participation effects and natural changes in behaviour, is required to confirm the finding. Part three is a critical appraisal of the meta-analytic review and empirical study. It explores the personal implications the empirical study has had upon clinical work. It also evaluates the empirical study’s web-based design, highlighting the methodological and ethical issues that were raised. Finally, the process of undertaking a meta-analysis is discussed, with specific focus on the challenges posed by this methodology
