Most of you reading this site is either working extremely hard to get FU money or has it already. If you're not prepared for it, it will just amplify your worst nightmares and habits, and there's a good chance the meaning of many things in life, including life itself, will disappear. Plan for a use/purpose for the FU money.
The journey is sometimes better than the destination, so make sure that once you arrive at the destination, it is only one stop of a longer journey. Here's a story of a millionaire who liked the journey much more than the destination, so gave away all the money to restart the journey. http://articles.moneycentral.msn.com/SmartSpending/blog/page...
After you've bought/rented all your material wants, you will feel an empty feeling and ask yourself, "that's it?", unless you have a purpose greater than yourself. Belong to a higher cause, whether it's joining a local non-profit or helping others (or start a yc? ;-). Money is a means to an end, not the end itself. Beyond buying power, money has no value unless it is used/invested/earmarked.
Here are some example people who were unprepared and how they used their FU money: http://www.oddee.com/item_97101.aspx
EDIT: Not sure why I'm being downvoted. Yes, we can talk about the great positives of FU money and the awesome power/material good it brings, but not about the potential downsides it'll bring if you don't keep it in check or plan for it in advance? For what it's worth, I've started several companies, each did well, and the points I've raised above were important for me (for belonging to a higher purpose, I sat on the board of a non-profit and helped raise money). There was a time when I thought I reached my "destination", only to feel that I had arrived at an deserted island.