Pistol squat with chair

Sit on the edge of the chair with a straight back, extend one leg and position the other leg on the floor, as close as possible to the imaginary vertical line extending from head through butt to the floor.
Extend your arms in front of you to aid balance.
Ball of foot and heel to the floor (do not balance on your toes, you should actually be able to wiggle your toes at any stage of the movement) slowly press yourself up to standing and in controlled movement sit back down again.
Repeat for the other leg.