If you could go back in time to change one event in history OR something in your life, what would it be?

So if any of you could change something in our history, could be ANYTHING, any event, anyone for good or bad. Or make a change in your own lifes timeline by perhaps going back and warning yourself about a future event that hasn't happened yet or maybe have a second shot at something, maybe that girl you've always wanted or guy, remove that "problem" out of the equation that you failed to do the first time in history.

Could be anything you want, but you can ONLY do it once and change ONE thing(of course depending what it is can potentially change lots of things)

Think of it as a One time Quantum Leap in a way or Back to the Future.

It can even be you preventing a comic writer from writing something you may not want or making sure another writer got the job. The possibilities are endless. Discuss and have fun!

I'm not sure what I'd do honestly, I'd more then likely do something to change my life for the better though.