HOW: Begin by positioning yourself on both knees, sitting back on your heels with your feet straight and thighs together, arms on the ground and your elbows touching the top of your knees. From this position, place on hand behind your head. Rotate your upper back and try to point that elbow up to the sky. You can also place that hand behind your back and rotate that way.
FEEL: You should feel a stretch in you mid back.
COMPENSATION: Avoid side bending as you rotate. You want pure rotation of the spine.