In a seated position, hold the ball with both hands at chest height, and lift legs off the ground to a 45-degree angle (or as close as possible). Twist from the core to tap the ground with the ball on each side of the body. The faster you twist and the higher you can hold your heels off the ground, the more you’ll feel the burn. Make it easier: Keep your heels on the ground instead of lifting legs up.
Stand with feet hip-width apart, holding the ball in both hands. Raise the ball overhead, and using your core and back, slam it as hard as possible to the ground. Drop into a deep squat to pick it back up and repeat, keeping the core engaged the entire time. Make it harder: Add speed or complete 20 reps, instead of 15, to up the ante.
Begin in a high plank position, then place the left hand on the medicine ball directly underneath your left shoulder. Inhale as you lower down into a push-up, and exhale on the way up. Switch sides. Make it easier: Decrease intensity by dropping your knees to the ground while keeping your core engaged.
Stand with feet hip-width apart, holding the ball at chest height. Keeping your gaze up (looking down can strain your back), lower into a squat. Then explode up to standing and toss the ball as high overhead as possible. Catch the ball and drop back into a squat. Make it easier: Press the ball overhead instead of tossing it.