Where You Begin

So I've been looking at all these blogs and posts on forums about creative people, and I have to wonder, "how do they do it"? Not just how they do the specific craft, because that part is easy enough to search for tutorials on, or to ask questions about, or to just pick some supplies up and start messing around. What I want to know, really, is how they can keep their focus on one project long enough, even just a several-hour-long project, to see the thing through to completion.

For me, if I can't finish something in 15-20 minutes, or have a reasonable partial goal ahead of me, I walk away. Sometimes I run.