Truth or Pleasure? I would like a robust philosophy that would work even when other people aren't around. — Kenshin
I agree w/ others' comments that there is no truly atomic, self-contained self, but I also agree w/ this impulse of yours - and I don't believe they conflict. Modern ethics is preoccupied with the problem of making society work - and well it should. But, assuming you've complied w/ Kant's categorical imperative, and you've done your job as a good utilitarian (assuming some satiable theory of utilitarianism), and you've done justice to all special obligations (family, community, etc.), in other words all of your other-regarding duties have been met - how ought you to spend your Saturday afternoon? Modern thought has sadly little to say about that. But Greeks and Romans had a lot to say about that. I would contrast pleasure with virtue, rather than truth. There are things you could do on Saturday afternoon that are daring, novel, generous, etc. They might not be fun.
Edit: You should do the daring, novel, generous stuff.