It's November. This means that something like half a million people are gonna try to write a novel in a month. Good luck with that. I firmly believe it can be done, because I've done it. The first draft of Enter Title Here was written in 31 days. And I wrote the first draft of my first YA novel (the one that got me my agent) in 8 days.
In fact, if anything I think NaNoWriMo isn't ambitious enough. The challenge is to write a 50,000 word novel in a month. Unless the book is MG or YA, that's too short to be saleable. Most people ought to be aiming for something more like 80,000 words.
As for how you do it? Well...you just do it. Trust me. It can be done. And the result can even be publishable.