Rest the stability ball on the ground and stand behind it. Carefully roll yourself out on top of the ball, walking your hands out on the ground until you are in a plank position with your feet on top of the ball. Keeping your core engaged, walk your hands back to the starting position behind the stability ball. Repeat, walking your hands back out until you are in full plank extension with your feet on top of the ball, hold for a full count, then walk back to start. Repeat for a total of 10 reps. For an added challenge, add a push-up at the top of the plank position