You can find this exercise on page 79 of the book Synergistic Golf.
Exercise Type: YOGA-STRETCH
Exercise Category: BALANCE, FLEXIBILITY, HIPS, LOW BACK
Stand sideways to a wall as you lift your knee closest to the wall up 90 degrees. Position the same hip against the wall to stabilize your hips. Inhale and lengthen your spine. Exhale and turn your belly button toward wall. Spread your hands apart on the wall below shoulder height. Hold for 60 seconds then switch sides.