I would choose and maintain a sleep schedule, or at least a bedtime (I'm not sure whether infinite willpower would let me wake up without an alarm at a given time, and I find that having an alarm set messes up the quality of my sleep).
I would do more things that I enjoy while I do them, but fail to muster the activation energy to manage - going for walks in nice weather, cooking more complicated foods, etc.
My ability to do things very fast is currently hampered by my psychological need to multitask, take frequent and extended breaks, etc. With infinite willpower I would just do things very fast. I would take on more paid work.
I would probably learn to drive, if controlling my emotions at will meant that I could do it without shaking like a leaf for hours after the fact or freaking out so much that I become an actual road hazard.
I would presumably be able to stop eating things after noting that I am neither hungry nor enjoying them. (I'm improved at this relative to how I was when I was a kid but it sometimes happens anyway.)
I would presumably be able to stop eating things after noting that I am neither hungry nor enjoying them.
This is actually theorized to be a major contributor to obesity. It definitely is for me; I generally desire to continue eating until mechanically full, or the food is gone.
Forcibly eating slowly (using chopsticks can help that) can help that.
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.