How? I take on too many things. Invariably, I procrastinate doing whatever by doing something else. As long as I constantly have a revolving list of "something elses" that need done, stuff keeps getting done. Sure, some things will never get done, but I find that when I have a big list, I am able to prioritize the level of procrastination I apply to each item. Thus, the things that never get done are things that I don't really need to do anyways. I try to force myself to work on those things... then I start procrastinating and I get all sorts of other stuff on the list done.
Maybe this doesn't work for everyone. That's fine. But not having enough projects is a terrible fate for me... because then nothing gets done.