Are there any difficult events in your past that made you a stronger person today? If you could go back and erase them, would you?
Honestly if I could really go back in time I'd make heterosexual marriage completely illegal.
(Note, I think marriage will probably suck for the gays too when they get their chance, but they need to learn that the hard way, just like straight people did. Plus, I can't wait until I can actually say "Get married? That's so gay!")