The one legged squat is an extremely effective leg and balance exercise which challenges your entire body.
If you find yourself waiting close to a set of stairs you are in a good position to do some one legged squats, or pistol squats are they are also called. Pistol squats can also be done on a flat surface but it’s easier if you do them on stairs, plus it’s good to have a bannister at hand to help with the balance.
The supporting foot should be placed flat on the ground and remain so during the entire movement. Your upper body should be leaned forward and your arms extended to help keep your balance. Slowly squat down and at the same time keep your leg extended straight, then push yourself up again. Keep your abs tensed during the exercise. Don’t rush! You can either do several reps on one side and then switch, or switch leg in between each rep.
Once you get stronger you can also do one legged squats on a flat surface, but keep in mind that this puts more stress on your knees.