HOW: Place a slider under the leg you do NOT want to work. The working leg is the leg that does not move. Slowly lower your body and reach out in front of you, then return back to the starting position by 'pushing' yourself back.
FEEL: You should feel all the muscles, especially your quadriceps muscles, in your stationary leg working to maintain your balance.
COMPENSATION: Do not put too much weight through the slider! Pretend there is an eggshell under your foot.