You can find this exercise on page 290 of the book Synergistic Golf.
Exercise Type: PRE-ROUND WARMUP
Exercise Category: FLEXIBILITY, LOW BACK, SHOULDERS
Sit tall in cart with feet together. Reach back to cart pole with right hand and place left hand on seat rail. Inhale to prepare. Exhale sitting taller and turn upper body toward right as hip remain still and quiet. Repeat five times each side (moving to driver's seat). Focus on breath and lifting of the spine away from hips.