The cardiovascular fitness, blood pressure, resting pulse, lung capacity and body fat of 246 subjects were measured and each subject completed activity, mental health and mood questionnaires. The results of this study support the hypothesis that participation in physical activity, rather than cardiovascular fitness, is the factor associated with better mental health and mood. Higher levels of physical activity were associated with better mood scores unless the individuals were unfit. This research has implications for how physical activity is prescribed; the emphasis needs to be on performing physical activity rather than improving fitness and should not be beyond the physical capabilities of the individual.