You can find this exercise on page 296 of the book Synergistic Golf.
Exercise Type: HEAVY BALL
Exercise Category: ARMS - HANDS, CLUB CONTROL - ACCURACY, LOW BACK
Stand with feet slightly wider than hip distance apart. Holding ball with bent arms in front of chest, squat down placing weight mostly in heels. Figure 8 ball around knees 10x one direction then switch directions. Focus on bending from hips and knees remaining in squat. Keep head and shoulders higher than hips and abdominals tight.