Lack of physical activity is one of the major causes for obesity and functional disability in the elderly. Including regular exercise in the elderly's lifestyle is not an easy task. The main objective was to analyse the effect of a motivational resistance-training programme on satisfying the individual's psychological needs, level of self-determination and body composition. A quasi-experimental study was performed with 47 volunteers (29 females, 18 males) of 67-75 years of age, divided into two groups: experimental (n = 27) and control (n = 20). A 12-week intervention programme was performed, with a total of 36 sessions. The results of the inter-group analysis indicated significant differences in the post-test measurement between the experimental group and the control group (in favour of the experimental group) regarding basic psychological needs. The experimental group, in comparison to the control group, significantly decreased their percentage of fat mass and increased muscle mass. Body weight and BMI values increased in the control group, while significantly decreasing in the experimental group. In conclusion, the motivational resistance-training programme in the elderly gave rise to positive significant changes at the physical, psychological and social levels, according to the definition of health by the World Health Organization.