When I start to do qigong, I contact my teeth/roof of mouth with my tongue, get into the first stance, begin the breathing, visualize the energy and say the password and all of a sudden EVERYTIME I feel this incredible uncontrollable yawn come on.

I can't quite figure out how to interpret it. What it means and why does it happen whenever I start to do qigong. If I do all of the above the yawn starts to come in the middle of the password. But I don't have to do everything. I can mix it up a little.

Has anyone else experienced this?

Any thoughts as to what it might be/mean? Maybe a little thought from the master?