Sit on the floor with knees bent, facing your partner. Your feet can be secured under a weighted or anchored structure. Hold a medicine ball with both hands.
Lie back with the ball over head and tap the ball to the floor. Immediately throw the ball to your partner from over head while sitting up. Partner catches the ball slightly above and in front of his head and repeats the steps. Continue to volley the ball back and forth.
Start slow, gradually increasing your speed throughout the set.