Stand about 2 feet away from a wall, with your back facing the wall.
Slowly lower yourself into a “seated” position with your back against the wall and your knees bent at about a 90 degree angle. Just hold that position.
You can start doing “reps” where you hold the pose for 30 seconds. Gradually work your way to holding the pose for 5 minutes or more!
Works your quads for running and cycling and especially skiing and sailing.