HOW: Lie on your side with the shoulder you want to stretch closest to the ground. You can put a pillow under your head for neck support if you want but it is not necessary. Bring your elbow to your side up to shoulder height. Using your bodyweight to pin your bottom shoulder down, slowly lift your elbow straight up with your opposite hand.
FEEL: You should feel a deep stretching sensation in back of your shoulder on the ground. You do not want to feel any pinching sensations or pain in the front of your shoulder.
COMPENSATION: If you are not feeling the stretch in the right area, try putting your elbow slightly higher than your shoulder. You can also try rotating your body backwards just a bit.