Stand with your feet wide apart, front foot flat on the ground, rear foot up on your toes. Stand up tall, with your shoulders back and your chest lifted. Center your weight between your feet. Tighten your abs and square your hips. Bend both knees and lower straight down toward the floor; do not pitch forward over your front thigh. Keep your front knee over your toes as you lower, shinbone perpendicular to the floor. Keep your torso vertical and your shoulders back; do not lean forward. Lower until your front thigh is parallel to the floor, then reverse the move to stand back up to the star.