I think David has the right idea, but is framing the problem in the wrong way. The problem is that startup founders don't know the difference between work and p

I think David has the right idea, but is framing the problem in the wrong way. The problem is that startup founders don't know the difference between work and play. When you're working, you better damn well be sure you're refreshed, thinking clearly, and working on something that is going to get you a desired outcome related to your business (i.e. meets the goal). When you're playing, who gives a shit?! Do what you enjoy and do it for as long as you want, AS LONG as your work is done. What happens more often than we suspect is that since we enjoy what we do so much, the lines become blurred. How much of those 14 hours of "work" were really aligned with a goal for your business vs. working on something that you just enjoy working on. If you framed that activity with the idea that this is "work" and that it needs to accomplish a goal and it needs to be of a certain quality, would you take it on at 9pm with your tired eyes? Probably not.