Supportive but resistant, relaxing yet energizing, water is the ideal medium in which to exercise safely the heart and lungs, muscles, and bones. Aim for a 20-minute swim 3–6 times a week. Water exercise is especially beneficial if you have aching joints: buoyant water supports body weight, reducing the strain on vulnerable areas such as knees and hips. Water resistance makes for effective toning and strengthening, especially of thigh and chest muscles. It also soothes puffy legs as water pressure encourages the movement of fluids back into the bloodstream, reducing swelling. Swimming promotes deep, controlled breathing and studies show that exercising in water boosts the immune system.