After warming up with five minutes of cardio, do the lying hamstring ball curl:
- Start by lying flat on your back with an exercise ball under your heels. Bridge your hips up and hold that position through the entire exercise.
- Flex your feet and dig your heels into the ball. Place your arms straight out to your side for support. (Don't use them during the move, though; they are just for support.)
- Slowly roll the ball toward your body as you curl your heels. Make sure to keep your hips in the bridge position; don't thrust them toward the ceiling as you do the move.
- Slowly return to the start position (straight legs, hips bridged) to complete one rep.
- Do 20 reps.