I believe our souls and "Spirits" as Apostle Jack puts it, are immortal.
But if I was stuck in the same body I think I'd get a bit bored after a time and would want a change of scenery, so to speak. But who knows, if I was born into the body of someone as beautiful as Kiera Knightly, maybe I'd feel differently. But even then, I wouldn't want to be stuck in an aging body that would fall to pieces over time so there are a lot of factors to be taken into consideration here.
Would I go insane? I doubt it, but based on the arguments I've put forward in the above text I think it would depend on the circumstances.