The growing size of world cities and ever more competitive working conditions are thought to cause subjective stress, anxiety and depression, with a resulting decrease in the quality of life, sleep disturbances, drug and alcohol abuse and poor productivity. Acute stress may suppress immune function, leading to an increased incidence of infections, and chronic stress may predispose to a number of ailments, including digestive disturbances, hypertension, ischaemic heart disease and neoplasia; jointly, these factors cause a substantial shortening of life expectancy. The control of stress thus makes an important contribution to health. Stress levels can be reduced by anxiolytic drugs, or by a variety of psychological techniques; however, an appropriate programme of physical activity may be the preferred option, since exercise has many positive effects on health that are unrelated to stress. If exercise is to be effective in inducing relaxation, it must be noncompetitive, moderate in intensity, and pursued in pleasant surroundings.