Use your thumb of your opposite hand to reach far back into your cheek
Gently bite to feel your muscle contract under your finger and relax
Gently pinch the muscle from the highest position and pull down towards your chin
You may also try to pull away from your ear and towards your cheek
Repeat whichever technique you feel is most effective
Make sure to use just enough pressure that you feel a stretch but no pain
Wash your hands or use gloves before starting the exercise
And share this video with someone that needs it.
Do this exercise 1-2x a Day
Remember we CANNOT prescribe specific exercises. So try them all but proceed with caution. If something doesn't feel right don't continue with the exercise.