I find this post interesting, because I wonder whether you really have periods where you can't work and therefore must do other things, or whether the other things get in the way of working. My default assumption is that website browsing keeps me from getting work done, because finding a cool website is instant gratification while serious work involves delayed gratification. Similarly, I'm doing national novel writing month right now, and I found my most productive fifteen minutes were when a friend said, out of nowhere, "want to see who can do the most work in 15 minutes?" It may have been the most productive fifteen minutes of my life, because the $0 bet meant doing semi-serious work = instant gratification, rather than the delayed gratification it usually involves.