When I am brushing my teeth, I'm bending my leg behind me, or I'm lifting my leg up and holding it in that position so I'm squeezing my butt in. I can do that while I'm washing or slicing vegetables, too. Or I go up and down on my toes, working my calves a little bit.
Some days I don't have time for a full workout, but I do have to dry my hair, right? So rather than just stand there blow-drying, I do several kinds of leg squats at the same time. I believe in multitasking.