You can find this exercise on page 265 of the book Synergistic Golf.
Exercise Type: PRE-ROUND WARMUP
Exercise Category: CHEST, FLEXIBILITY, SHOULDERS
Stand at a corner wall. Place left hand on the wall, keeping arm parallel with floor and arm straight. Slowly turn your body and feet to the right away from the hand on wall. Focus on lifting through the spine. Exhale as you gently push against the wall and turn more. Hold for 10 seconds each side.