what now?

Michael Phelps has broken all the records possible at the 2008 Olympics with 8 golden medals. I haven't seen any of his performances, I admit, since I don't think it's gonna add value to my life. However, I am curious to know how do you live the rest of your life after being crowned the best swimmer of all times? Is it all downhill from there, is he going to play the "I'll beat-my-own-scores-game" or will he live a simple life with all the money he won and train new champions?