Retiring at 24?

Five-times Olympic gold medallist Ian Thorpe is retiring at 24, an age when most are taking their first tentative steps on the career ladder. But if you've achieved your goals so young, what do you do next?
Well, I'm not sure I'd have a problem but I can understand that retiring due to health or aging reasons as an athlete might have to would mean a complete career change. But retirement due to having enough money to live on wouldn't be a problem for me at all. What would you do with your days?