Stand with a sturdy bench or fitness step (with two to four risers) on your right. Place your right foot on the step, leg bent, left foot on the floor. With abs tight, straighten your right leg, pulling yourself up using just your right leg and butt muscles. Return to starting position and complete set; switch sides.
To help target the butt, imagine pressing your heel firmly into the step each time you lift yourself up.
Tip: Stand tall and avoid leaning forward as you step up.