Assume a modified pushup position, with your forearms resting on the floor. Your elbows should be under your shoulders and bent 90 degrees. Keeping your torso steady, raise your right arm forward and to the right, so that it points to 2 o'clock. Hold for 1 to 2 seconds, then lower your arm and repeat with your left arm, raising it to 10 o'clock.
The plan: In week 1, do eight repetitions. Do 10 in week 2, and 12 in weeks 3 and 4.