This is absolutely true for me as well. I'll turn something as simple as writing a blog post into a gigantic project because I'm too strict with what I output. If the open source tool I'm working on doesn't perform quite as well as I'd hoped, I have pessimistic visions of it being wholly useless. If a homework problem stumps me, I simply cannot skip to the next problem or else I feel I've been defeated. Pessimism, combined with really caring, is strongly connected to procrastination.