The 'tip-toes' exercise strengthens the calf muscles but is also useful to re-train proprioception (spatial awareness and balance of the limb).
If you have problems viewing the video, here is a set of still images to show you the exercise.
|Stand comfortably near to a support, such as a wall.|
|Go up onto tip toes for 5 seconds.|
|Relax. Repeat 5 times.|