The work itself is simple. Take a sore back: By resting your aching back on the grapefruit-sized balls and letting your body sink into them, you're unworking the muscles that hurt. Pain and tension drain out of the body. Petrone shows how proper breathing (which she demonstrates) works in conjunction with a range of unexercises that call for placing the balls under the back, head, knees, hip, elbow-wherever there's pain-and then resting, rolling, or rotating on them. She points out that relief can come in surprising ways: Lower back pain may be helped by placing the ball under your neck, or a bad knee might be helped by hip work. It's a revolutionary program of relief, from head to toe.