Step 1: Lay down with your back flat against the floor and your knees bent.Step 2: Take the medicine-ball and hold it with both hands over your head so that it touches the floor.Step 3: Sit-up using your abs and as you sit-up take the medicine ball over your head and throw it at the wall in front of you.Step 4: Catch the ball and return to starting position. This completes one repetition.