It is really hard to keep going. My schedule is different this year (last year I did most of my writing in the morning, this year I am doing it later, because I have stuff to do in the morning).
I have to keep on top of it, otherwise I would never complete it. The first two or three days were the worst, because I wasn't really sure I wanted to do it this year. But I am over a week into it (and over the 15k) so I'd be an idiot to give up now!
Keep going and Good luck!