In the YouTube video below, I use a yoga therapy ball, but a lacrosse ball, or tennis ball works also. While standing, place the ball on your upper pec, and press your chest into the ball, and the ball into a wall. Hold this pressure for five minutes, and then switch sides. I watch TV while doing this stretch so it doesn’t seem as long, or boring. Ideally, perform this stretch daily, but the first time you try this, your upper pec might be sore, so you may want to take two days off before applying pressure with the ball again.