Yeah, the "It doesn't have to be perfect" and the "C'mon, you can eke out two sentences here, right? Five minutes, I swear, then you can go back to screwing around," things seem to work best for me. Otherwise I get all tangled up in guilt and anxiety and THAT doesn't help. But if I get into a project just a liiitttle bit, often enough my brain will engage and you'll end up having to pry me away. Not always, but sometimes. And if not, I got five minutes of writing done? It sometimes helps to have an intermediate goal after that, too--200 words, or 15 minutes, or whatever.