Benefits: Strengthen your hamstrings and glutes with this seemingly simple move, while also engaging your core.

• Lie with your back flat on the floor with the back of your calves on top of a stability ball and your legs straight.
• Brace your core and squeeze your glutes to raise your hips off of the floor so that your body forms a straight line from shoulders to heels. This is your starting position.
• Drag your heels to roll the ball as close to your butt as possible or until your knees form 90-degree angles.
• Pause, then slowly straighten your legs as you roll your feet away from your glutes, returning to the starting position.