The use of exercise for improving health has been the subject of research for several decades. Studies have shown unequivocally that exercise is beneficial for preventing and/or treating numerous medical conditions. With the U.S. population increasing in age, use of exercise to ameliorate the effect of illnesses related to aging is therefore of great potential value. Despite this information, most members of the population do not incorporate physical activity into their daily routine. Because aging often is associated with diminished quality of life, we reviewed the literature to assess whether exercise is of value in maintaining a person's functional capacity as he or she ages. Available data suggest a positive relationship between higher levels of fitness and higher functional state/improved quality of life, both in healthy individuals and in those experiencing specific ailments commonly seen in an aging population.