You can find this exercise on page 243 of the book Synergistic Golf.
Exercise Type: YOGA-STRETCH
Exercise Category: CHEST, FLEXIBILITY, HIPS, LOW BACK, SHOULDERS, STRENGTH
Stand tall with feet a lot wider than hip distance apart. Turn right foot to right. Arms out to sides parallel with floor. Inhale and reach right arm out over right foot bending at the waist and reaching hand to foot. Allow right hand to rest on right ankle while left arm reaches toward the sky. Turn head to look at left arm. Squeeze all muscles tight while still lengthening through joints. Hold for approximately 10 seconds. Switch sides.