I've known a lot of people over the years who call themselves writers, who love to talk about writing and all its aspects and who are thrilled to discuss their books in particular with you if you ask. But there's one problem: they don't write.
Oh, they do, but they wait for inspiration.
Unfortunately, contracted deadlines don't wait for inspiration.
Writing is a lot like anything else: the more you do, the more natural it feels. (I was going to say "the easier it gets," but that's a lie. It's rarely easy. It's constantly learning, practicing, working, improving.) If you write on a regular schedule, odds are that your story is going to flow regularly, too. Writing's an art, but it's also a job, and unless you're luckier than me, you have to do a job whether you feel inspired or not.
I read a quote -- wish I knew who said it: "I only write when I'm inspired, so I make a point of being inspired every morning at 9 a.m."
When wanting to tell the characters' stories isn't enough to get me to the computer, the inspiration of a deadline does the trick.