Sit in a split squat with a half-butt on a chair in a narrow stance.
Keep your weight over the front over your foot.
Keep your knees in line with your toes and over your toes.
Keep the angle of your front shin fixed all the time (ankle flexion)
Keep your torso fixed.

1. Extend your legs and stand up. Drive your core forward over your front foot.
2. Band your knees and sit back on the chair. Relax muscle tension in a sitting phase