The secret to doing this move with perfect form? Imagine a dog at a fire hydrant.
Why you should do it: Few moves can isolate the outside of your glute muscle (also known as the "perky butt" muscles) as well as the kneeling leg lift can! You can make it harder by fully extending your leg, or try lifting your opposite arm at the same time to challenge your balance.
How to do it: Start on your hands and knees. Lift your right leg straight up from the hip, taking care to keep your heel in line with your knee. Pulse at the top 10 to 20 times, lifting and lowering your knee one or two inches. Lower leg to original position and repeat on the other side.