Bring one arm straight across the front of your body at roughly shoulder height. Hook your other forearm above or below the elbow and gently pull it closer to your chest. Keep the shoulder of the stretching arm pressed down away from your ear rather than hiking up to meet the pull — that's where the stretch actually lands, through the back of your shoulder. Turn your head away from the stretching arm and you'll usually feel it open up a little more. Keep your torso facing forward instead of rotating with the pull; twisting just borrows range from your spine instead of your shoulder.