Stand still on the ground. You can help yourself by holding at some nearby bar or wall. This will be your starting position.
Raise your a heel of one feet and keep in this position for a required amount of time. Ensure that the knee is kept stationary at all times. There should be no bending at any time.
Go back slowly to the starting position as you breathe in by lowering your heels as you bend the ankles until calves are stretched.