No, I'm not talking about character arcs, which is an entire post in itself. I'm talking about your own motivations as a writer, be they external (e.g. editor deadlines) or internal (e.g. desire to hit the NYT Bestseller list). I've always responded really well to deadlines, whether self-imposed or other-imposed. I knew I needed to finish revising (okay, re-writing) the second half of my book for a writing retreat I'm attending this week. I finished yesterday with two days to spare, but as excited as I am about the retreat (my external deadline), that wasn't the only motivation behind my late nights this week.
Last week, I mentioned my obsession with Shiny New Idea. I was so motivated to start it, but wouldn't let myself until I finished my "old" manuscript. Last night, I literally hit the "compile" button in Scrivener (coolest program EVER) for my old document, then opened up a new one and wrote the first chapter of SNI. The internal motivation to get my new idea on paper is what helped push me through the torture of a bazillionth revision (only a slight exaggeration) of my last ms. I get so geeked out over first drafts that I'm going to enjoy this time while it lasts...after all, I know that first revision is just around the corner.
What about you? Are you motivated more by external or internal factors?