You don't necessarily need a medicine ball for this "medicine ball hand walk" exercise. Men's Health will show you exactly how to do this abs workout exercise. If you struggle to get started with this core muscles exercise, then try replacing the ball with a small step.
Assume the classic press-up position with a medicine ball next to your right hand. Place your right hand on the ball. Now lift your left hand off the floor, balancing briefly on the ball with just your right hand.
Next, place your right hand on the floor to the right of the ball, and then place your left hand on the floor next to your right hand. The ball should now be next to the outside of your left hand. Repeat in the opposite direction. That's just one rep.
If you struggle to get started with this core exercise, try replacing the ball with a small step until you get used to both the balance and walking on your hands from side to side. When ready, have another go on the ball.