This is similar to my experiences with getting blood drawn. About two-weeks prior to the draw I would watch a couple of videos on YouTube of blood draws each night. By the time the day came, I was still anxious but fine.

I've been told that the anxiety was created by my nearly passing out when getting blood drawn but the mechanism for nearly passing out is different from panic or anxiety. Still, my "exposure therapy" worked. The last time I had my blood drawn I watch a couple of videos the night before but probably didn't even need to.