Feeling arrogant? Sort through a pile of papers that have been tucked away in a drawer for a few years and stumble upon a handful of letters and assorted scribblings that you wrote while in the middle of an unpleasant breakup. That'll take care of that swollen ego real quick.
There is very little I wouldn't give right now for the ability to travel backwards in time so that I could kick my own ass. Jesus, what an idiot.