Since September, I've been putting some money in the bank each paycheck because I wanted the time to write this summer instead of teaching a summer course. This is in part an extension of the "book review mantra"; I can manage with less money (I hope), given what I've saved, but I can't get back the writing time that I'd usually spend grading and teaching.
Now here's the part that sounds a little crazy: what I've saved isn't exactly as much as a summer course, but I'm thinking of it as my salary for the next 6 weeks. I have $X amount per week, and thus $Y amount per day, that I am paying myself to write. If I don't write, I'm not only wasting time; I'm wasting money. Every day I don't write is not simply a day that I could have gotten some writing done; it's a day when I could have been teaching and making money instead.
In a way, it's not terribly different from what we usually do when we think about writing and productivity. Somehow, though, having to account for that $Y at the end of the day as well as for a word count seems to give the whole thing a different twist.