You can find this exercise on page 55 of the book Synergistic Golf.
Exercise Type: CARDIO
Exercise Category: CARDIO, LEGS - FEET, RHYTHM - TIMING
Side shuffling increases strength in inner and outer thighs. Stand with feet slightly wider than hips. Step right foot toward the left foot then follow with the left foot stepping farther left. Steps will be r-l-r-l-r-l. A slight hop may be added for speed. Be sure to pick up feet vs. drag them. Shuffle 20-30 steps one way then reverse. Take turns doing forward and backward walking.