I am a total convert to the "don't break the chain" idea. I started writing a book on game programming[1] about four years ago. At the time, I was working at EA, miserable, and highly motivated to have the book done so it could help pad my resume. I got a book deal (O'Reilly) then, when that fell through, another (Apress). I had a real writing schedule, and a very supportive wife, and I would work on it for hours at a time.

Then I left the game industry, moved across the country, and had another kid. Suddenly, motivation and time were scarce. I backed out of the book deal and basically put it on hiatus for two years. I still really wanted to finish it but it just wasn't happening.

About a year ago, I realized that if I didn't finish it soon, I never would. My familiarity with the domain was fading every day. I didn't want the project to be a failure, so I decided to try writing every day.

I didn't have a set goal each day, but I try to do around 30-45 minutes. That ends up being ~500 words of first draft, ~1,000 words of later revisions.

In the past 309 days, I've finished 12 chapters. That's 59,568 words, plus a few thousand more for intro sections. I've redesigned the site twice, set up a mailing list, gotten a business license, and a bunch of other grunt work.

I'm about halfway through the very last chapter now (!). In less than a month, I should be able to say the book is done. (Though what I mean is that the manuscript is done, I'll be doing ebook and print versions after that.)

I absolutely could not have done this without working on it every day.

    [1]: http://gameprogrammingpatterns.com/