HOW: Sit on a box/bench/object of the desired height. The taller, the easier. Stand up from the box using both of your legs. Once standing, shift all your weight to one leg and lift the opposite leg in the air. Slowly lower yourself down to the box with only the one leg. Repeat
FEEL: You should feel your glutes, quads, and core working to slowly lower yourself down to the box.
COMPENSATION: Try not to lean over to one side with your shoulders. Use your core to stay as centered as possible. Do not let your knee dive inward or outward excessively.