People with a mental illness have very poor physical health parameters when compared to the general population. This paper outlines an exercise programme developed to improve overall fitness and curb weight gain. Seventy-two mental health service inpatients completed the general or individualised gym exercise programme within 12 weeks. Baseline and end of course physical health parameters were recorded, along with test results on a number of fitness, strength and agility tasks. No statistically significant differences were found between average pre and post programme weight scores, and weight did not increase over time. Significant differences were found on strength and agility tasks, and a decrease was observed in average resting and post exercise heart rates. Average blood pressure did not change, but the number of baseline readings indicating hypertension reduced from 14 to 8 people. The exercise programme was successful in improving the physical capacity of the individuals who participated.