Answer from Justine:

The fatty part of the thumb should rest above the collar bone while also touching the sternum, pressing down (fairly firmly) to stabilize the origin of the muscle. Take the other hand and hold the thumb in place. Then, take your head back slowly, and then diagonally away from the hands, you should feel a strong stretch in the side of the neck, possibly up to behind the ear. Move your head gently to explore where you are tightest, when you find it, hold the stretch and breathe into it. Pause between sides to notice the difference, you should feel very warm on the side stretched. Hope that helps!

Answer from Sherry:

You’ll know you are holding the origin of the muscle if you feel the muscle stretch and lengthen as you nod your head up and down.