Start on your hands and knees with your weight evenly distributed and your neck parallel to the floor. Slowly extend one leg straight out behind you and hold it parallel to the floor. Your foot may be pointed or flexed – whichever is more comfortable for you. As you extend your leg, don't let your back, head or stomach sag. And make sure no one is behind you when you do this move. Hold for 5 seconds. Return to the starting position. Do 5 repetitions. Switch legs and repeat the exercise.