Use a sofa cushion to improve your balance. Stand one-legged on the cushion and move a medicine ball (or a 1-gallon milk jug or heavy phone book) from hand to hand, side to side, and behind your head. Once you’ve mastered the move, try it with your eyes closed. “You’ll improve your balance, coordination, and body control, all important athletic attributes,” says Greg Brittenham, assistant coach of player development for the New York Knicks.