One-Arm Cross-Shoulder Extensions
Lie flat with back on a mat with knees bent and a light dumbbell in your right hand. Raise the weight over your head, arm pointing straight up, with the dumbbell facing left. Place your left hand on your right triceps to help support your right arm. Slowly lower the weight to the left until it lightly touches your left shoulder, keeping your wrist straight and your right upper arm still. Raise the weight back overhead, then repeat 10 to 12 times. Do one set, then switch sides.