There are two ways to approach this. One is to keep doing this lesson, but have the primary focus be on your jaw and keeping it loose. Do the movements, but notice your jaw. As soon as you feel it tightening, think about it being soft and loose.
The other approach is to work with the underlying aggression that is probably stored in the jaw — this is almost always why jaws are chronically tight! Review the Healthy Aggression Lesson and also the Vooo-Ahhhh lesson with this jaw tension in mind.