This exercise may look easy, but it's guaranteed to get your buns and hips burning after just a few reps. Bonus: This move also engages your obliques.
Sit with your right knee bent and turned out to the side, resting on the floor in front of you. Bend your left knee behind you on the floor, with your foot tucked into your body. Lean forward slightly, placing your hands lightly on the floor in front of your right leg. Lift your left leg off the floor a few inches, point your toes, and keep your left heel in close to your body.
Extend your left (back) leg out to the side of your hip, keeping your leg lifted slightly off the floor. Bend your knee and draw your left heel back in towards your body, keeping your leg lifted. That's one rep. Repeat 20 times with the left leg, 20 with the right.