While in a regular prone push-up position, place your hands on the top sides of the ball with your
fingers pointing downwards. Push your hands in towards each other to increase tension on your chest.
Feet are shoulder width apart but can be slightly wider or narrower. Simply press your bodyweight
off the ball, hold and lower in a controlled fashion. The straighter your back, the harder the push-up.
A very advanced variation would be to use two swiss balls, one for each hand.
Stability Ball Push-Up (Hands on Ball) Exercise - Start Position
Stability Ball Push-Up (Hands on Ball) Exercise - Finish Position