I am the same way. I've decided that I'm going to have two projects ongoing: one will be challenging that I can work on in short sessions, the other will be easier with more immediate satisfaction. I figure I'll go through several quicker projects before I finish the harder one, but this way I can stretch myself without overloading myself and getting frustrated. I also have decided that I won't set deadlines--that is what makes me anxious--this is supposed to be fun!