<iframe src="https://player.vimeo.com/video/271020434?background=1&quot; width="640" height="360" frameborder="0" allowfullscreen></iframe>

While laying on your stomach on a chair or low bench, lift one leg up squeezing your glute then returning to the ground, then repeat on the other leg. Keep alternating while focusing on lifting only with your glute. Try to not arch your back.