Quadruped Thoracic Rotation

Get on all fours with your hands under your shoulders and knees under your hips. Place one hand behind your head, elbow pointing out to the side, and rotate your upper back to bring that elbow down toward the opposite forearm on the floor. From there, rotate the other way, opening your chest and turning your elbow up toward the ceiling as far as your upper back comfortably allows, following the movement with your eyes. Your hips should stay still and square to the floor throughout; if they rock with you, the rotation is coming from your lower back instead of your upper spine.