HOW: Get set-up laying on your side, you can use a pillow for head and neck support. With the arm that is on your side, elevate up until your arm is straight up and down. Slowly lower back down until your arm is at your side and repeat.
FEEL: You should feel the muscles on the outside and behind your shoulder working.
COMPENSATION: Do nut shrug your shoulder, do not allow your body to rotate forward or backward throughout this exercise.