For the past few years my willpower has been steadily increasing. If it lasts and I use it to accomplish something noteworthy, I might write a post about it.
Anyway, what should a rational preference utilitarian with infinite willpower do? Assume that there are no negative effects (unhappiness, stress) with using this willpower, and that they can control their emotions at will.
Clearly they should work a lot more, not spend time on recreation (movies, TV, games), stand instead of sitting, etc..
What else? Should they listen to music? Should they keep their muscles flexed 24/7 ? What should they learn, where would they have the most relative advantage? How much time would be worth spending on social interaction?
I can figure out these things on my own, but those questions are important and good ideas are very valuable.
My plans wouldn't drastically change. I would still work on the projects for which my participation yields the the greatest increase of the probability of a sufficiently positive outcome of a technological Singularity. But having infinite willpower would have the surprising disadvantage that I couldn't experiment with increasing my willpower anymore. So, my advice when it comes to willpower increasing would be pretty bad (unless I know how to generate infinite willpower of course).
Basically, I would just get more important stuff done. I would forgo all purely recreational activities, as they aren't as important as improving the world and securing its existence and quality.