This document provides instructions for a tennis ball therapy (TBT) exercise to relieve jaw pain caused by excessive clenching or tension in the masseter muscles. The masseter muscles are responsible for closing the jaw and can become sore or tense from overuse, such as from prolonged smiling, dental surgery, or from keeping one's mouth shut due to stress or abuse. The TBT exercise involves using a tennis ball to apply pressure and massage the masseter muscles on both sides of the face through gentle movements of the head to relieve tension and pain. Following the TBT instructions could provide headache relief and help "get rid of the pain once and for all" by releasing tightness in the masseter muscles.