Another good question would be: what do you want to do when you are at 50?
heu... retired ??
Blegh, that's insanely boring and mind-numbing man. You shouldn't stop working, you should work less.
it's not like "stop working" it's just stop working for someone, if you managed your 30 years at works well, then at the age of 50 you should be able to cover your financial needs from the money you've been storing and then just like heisenbergman
it as an opportunity to spend more time with family and pursue other interests full-time without having to worry about earning money.
one of the activity i may want to do at that age is teaching kids the basics of programming
that will make me feel like a damn boss