You can find this exercise on page 155 of the book Synergistic Golf.
Exercise Type: BIG BALL
Exercise Category: BACK, CHEST, FLEXIBILITY
Kneel with hands stretched out in front of you on top of ball. Slowly sit back into heels while walking ball as far as you can away from you. Lower head down underneath elbows and feel stretch throughout arms, chest, and back. Focus on breathing. Hold for 10 seconds and repeat 3x.