Working the arms independently makes the core work to stabilize your torso while you work your chest.
- Lie on your back with your heels about a foot away from your butt. Hold a dumbbell in your left hand and bring both hands to the ceiling.
- Bend your left elbow, lowering your upper arm to the floor. Exhale and straighten your elbow, pressing the weight back to the ceiling to complete a rep.
- Do five to 10 reps on each side.