I've learned to limit my guilt about limiting my plans and commitments. ;) It turns out that I can actually make progress on things that really matter. For everything else, it's okay if I take a long time to get around to things.

I think limiting your guilt and frustration is the key part. If you let yourself get discouraged or frustrated by the number of unfinished projects you have open, then you're wasting energy beating yourself up. Better to accept that you're focusing on one or two at the moment, keeping a few more on the back burner, and putting other things away for now or for a long time. =)