HOW: Stand up leaning the back of your shoulder against a lacrosse ball or mobility ball into the wall. Cradle your arm against the ball with your opposite arm to keep it relaxed, from here you can work on the muscle. You have the option of going up and down or side to side, whichever feels more productive for you. Two options you have to make this mobilization more aggressive include bringing your feet away from the wall so that you are applying more pressure into the ball OR stretching the muscle by bringing your arm across your body as you perform this mobilization.
FEEL: It is common for the soft tissue in this area to be sensitive. You shouldn’t be putting pressure on any bones in this area, make sure it is soft tissue (such as muscles and tendons).