5. Do eight to 10 total reps for three sets. Modification: To make this movement easier, plant your feet on the ground and only lift the leg that you're feeding the medicine ball under on each rep.

you should aim to perform 1-4 sets of 8-15 repetitions per exercise, he says. You can adjust the ball weight you're using for each exercise, as you would with dumbbells. When to use a medicine ...