I've been struggling with the same phenomenon in all my jobs. Currently I'm working on a "dream job" in well-know Open Source company, I should be happy, except that I'm not. I actually enjoy my work when I work on a problem during the weekends, outside working hours. Nobody is breathing down my neck, I feel free. As soon as the work week starts, the same task I enjoyed during the weekend suddenly doesn't feel enjoyable anymore and I kind off lock up and I'm not able to perform as well anymore.
Anyone else familiar with this feeling and what to do about it?
Get it wrong, your supervisor does a supervisor's dance.
Get it wrong, someone is laying cold.
Both types of work is necessary and important.
Coping is not mistaking one type of pressure for the other.
Good luck.