Yeah, I had the EXACT, if not very similar feelings the first time I PRed. I didnt' know what a relaxed and flexible process the photoreading step was, so when I was interrupted the first time, I got very angry. Then I was mad afterwards because I thought I had done it wrong. Sometimes I also get headaches and eyesores (as previously mentioned) while PRing which induces stress, but I've become better at calming down.
For me the key is release, be relaxed and just let your mind absorb the pages.
