You can find this exercise on page 2 of the book Synergistic Golf.
Exercise Type: STRENGTH
Exercise Category: CHEST, SHOULDERS, STRENGTH
Hold a pushup position for 30 seconds. Watch in a mirror to ensure straight alignment of shoulders, hips, knees and ankles. Do not lift buttocks up or let them sag (which compresses low back). Once 30 seconds can be held comfortably, move on to level two by lifting one arm and rotate.