I had an interesting thought while corresponding with an occasional reader of this blog who's trying to write her first novel, and complains about being completely convinced anything she would put together would just completely suck. I believe this is known in the analyst trade as a 'lack of confidence', and it's one of the two main reasons people don't manage to fulfill an ambition of writing a book. The other reason is, careers. People with careers tend to have to put those careers first, unless they're prepared to go so far as putting that career to one side and concentrating instead on the bookwriting.
There's a movie called New York Stories which is a series of short films about New York by various directors released as a single picture. One of the movies stars Nick Nolte (I think) as a successful artist who suffers from constant doubt. In this respect, he's a very typical artist (or writer, or whatever); there's a scene where his agent tries to persuade him to get started on stuff for this year's show.
"Forget it, I don't have it any more. My stuff sucks." (or words to that effect)
"You say this every year," comes the agent's reply, exasperated. "And every year you do the show. And then it comes round again."
"This time I really mean it," he says. "I've lost it, Louie (or Malcolm, or Lennie, or whatever it is). I'm not doing a show this year."
Of course, he makes the show. Everything goes great. This is remarkably like the process that goes through the minds of, I'd say, the vast majority of writers. If you want a motivating emotion for writing a book, you'd probably have to assign a big chunk of it to fear. Not just fear of personal failure, but fear of failure in front of both your peers and the reading and writing community as a whole.
When I wrote my first book, Touched by an Angel, I wasn't working, and during those six months of unemployment I found the will and the time to write a book. I tell you this because I think there might be people reading this who feel they lack the skill or the talent to write a decent book. Well, maybe you're good and maybe you're bad, but you'll never know until you actually do it.
The way I worked it out in my head was this: even if I only wrote twenty words in a day, it was twenty words more than I'd had before. Also, I would not stop if I thought my writing sucked. That wasn't the point - it shouldn't be yours either. I wanted to finish it more than I cared if it was any good or not. The point was, did I have the stamina to write a minimum 100,000 words of consecutive text? Yes I did. Persistence is to some degree the mark of a writer. Is your writing good, bad, whatever? Doesn't matter. You just write. That's your motivation; not to be good, or to be bad, because these are value judgements you can ill afford, when you run the danger of the little voice in your head telling you you aren't good enough, that of course your writing sucks, and you're wasting your time. The mark of a writer is in the ability to ignore those voices of doubt and DO IT ANYWAY.
Remember; for every thousand talented writers, there are maybe a half dozen at most who ever actually do anything about it. Everyone knows someone who could out-write a famous novelist - a someone with maybe one story published in a small-press. You hear about this kind of thing. Frankly if it isn't used, if it's left dormant, talent is worthless, literally worthless. If you're a talented writer and you do something about it, then you're lucky because you have a good shot at recognition. As for the rest of us, we may not write the next Harry Potter or To Kill a Mockingbird, but if we persist we stand a chance at enjoying a career that makes us feel like we're engaged in something worthwhile, that gives us a far greater sense of satisfaction and creative enjoyment than many 9 to 5 jobs do.
For myself, that first book never sold. It got me an agent, but after three years it didnt' sell. Pan liked it, but not enough to buy it. They asked if I had anything else, and as it turned out I'd just started out the first draft of Angel Stations a few months before, having not written anything novel-length for a few years. As I'm sure you know now, they bought Angel Stations. I'm already a quarter of the way through the second draft of my second book. The lesson being: persistence is everything. Touched by an Angel may not have sold, but I did gain the experience of what it felt like to write a book, to be able to quantify the experience in my mind, and that's what made it possible for me to write further novel-length material.