HOW: Maintain a single leg squat position on one leg. With your opposite arm, pull your elbow just to your back. As you pull, do not let your body come forward. Keep your weight on the balls of the feet the entire time.
FEEL: You should feel your quadriceps muscles fighting to maintain stability while you perform the row.
COMPENSATION: Do not let your knee change angle. And do not let your body fall forward when rowing.