Leg raise
This is a great exercise for warming up the gluteal muscles, which also helps to learn how to keep the pelvis on one leg. It is mandatory for athletes, in particular for runners.
How to do this exercise:
Stand with one foot on a small elevation, such as a step. Raise the opposite thigh and pelvis, hold for 3-5 seconds. Then slowly lower to the floor. Repeat the exercise until you feel tired (usually 1-2 minutes), then change your legs. Make sure that the working leg is straight and that the shoulders do not roll over to one side.