Immortality - specifically, zero aging, immunity to disease and any physical damage is quickly healed until I'm good as new - seems to me a terrible torture. Oh sure, there's humanity and all their antics and electronic stuff and Final Fantasy 250 and that's all fine and good. Until you're 1,000,000 years old and the human race has either died out or bred out of existence with alien races. Alright, that's fine, alien races are pretty cool too. Another couple million years pass and you're now one of the few remaining living organisms in the galaxy. Well, whatever, you're immortal, just set course for another galaxy and set off. You have the time, after all.
Somewhere in the middle of it all, the galaxy Andromeda ghosts through the Milky Way, scattering both galaxies in a cosmic cataclysm seldom seen in your entire impressive life-span. But it's cool, you live through it. Anyway, off to another galaxy. It takes a few more million years of absolute solitude, though. It's around here that insanity FINALLY sets in.
And you still have the rest of eternity ahead of you.
Unless you suicide in a supernova... or a vat of obscenely strong acid. Or something like that. Just saying, I don't care how powerful your healing abilities are, you jettison yourself into a supernova, the matter that makes up your existence is turned into completely different matter. You just don't get more dead than that.