HOW: Begin this exercise upright. Keep the hand of the side to be stretched behind your back. Bring your ear towards the opposite armpit (here I am showing the Left ear to the Left armpit). This requires you to flex your head forward, sidebend away, and rotate towards the side you want to stretch.
FEEL: The upper trap (muscle on the side of your neck) being stretched.
COMPENSATION: letting the shoulder girdle elevate on the side of the neck that is being stretched.