1. Sit in a chair with your back straight, your core engaged. Grip the seat of the chair lightly for support.
2. Cross one leg over the other, at the ankles. Exhale and extend your bottom leg until it is completely straight and parallel to the ground. (The top leg will lift as well, but keeping it relaxed will allow it to act as a "weight" for the active leg.)
3. Do 5 reps of lifting and lowering, then hold at the top for 10 seconds. Repeat 5 times.
4. Straighten both legs and lower to the ground, pause, then re-cross with the opposite leg on top. Repeat exercise with opposite leg.