But writing is a fantastic start.
Which is why NanNoWriMo exists.
NanNoWriMo is a chance for authors all over the world to egg themselves on to finishing a novel within a set time period. The point of the season is to get authors to finish writing their books, rather than tossing them aside when they're halfway through. There are a number of useful principles an author can draw from the concept of NaNoWriMo, so that any or every month can be this ... er, productive. Or horrific. However you see it.
Focus is the writer's friend. When you have a deadline, you're less likely to go surfing the internet or checking your feeds on social media. Also, you're way less likely to start a new project when you're only a third of the way into your first. Focus means that you can't think of anything else. It takes up a great deal of your thought life, and the most important thing is to get it out - so that your brain doesn't feel like it's going to blow up. It's kind of like memorising "The Highwayman", by Alfred Noyes. Or maybe more like "Paradise Lost", by John Milton. You have to get it out before you forget it; it's weighing on you. Now is the time.
Writers are very lonely creatures, and one of the greatest things about NaNoWriMo is that people all over the place (whom you've "met" virtually on social media sites) are doing the same thing as you. It's like running a marathon with a whole lot of other people, rather than running a marathon on your own while the audience throws tomatoes.
I've half covered this in the "Focus" section, but I felt it was important to write about separately too. NaNoWriMo gives you a deadline, but that also means that you start thinking in smaller goals and time frames, to make everything more manageable. It's like what Braden says above ("If I were you, I would go for the seconds. There's a lot more of them"). You start thinking like this: "17,250 words a week; approximately 2,400 words a day" ... I always take the Sunday off, because I'm a Christian. So that puts me up to about 3,000 words a day, six days of the week. But you get the idea. Each day, you have a goal of how much you want to do. You have direction.
So here's how we can learn from NaNoWriMo and get our books written without it! Focus: shut down the internet - even switch it off if you don't need it for research. Give yourself a deadline. Companionship: find other writers that you can contact for encouragement and help. Goals: have a daily goal to help yourself get through it. Don't let yourself eat chocolate, drink coffee, watch TV, or whatever until you've done what you need to do.
And then every month can be a NaNoWriMo. Erm ... great thought, right?