HOW: Get set-up next to a wall or doorway and place your hand on the wall down by your pocket with your palm against the wall, there should be some space between you and the wall. Focus on keeping your shoulder and shoulder blade in a good position by keeping it back, then perform the pec stretch by leaning your body forward and maybe rotating your chest away from your hand.
FEEL: You should feel a stretch in your pec region below your collar bone and the front of your shoulder. You shouldn't feel any numbness or tingling or pins and needles in your arm/hand, if you do back off.
COMPENSATION: Try to focus on just a pec stretch, do not lean too far forward or rotate your chest too far away. Don't let your shoulder fall forward, keep your shoulder blade back.