Really sit down and ask yourself do you really want to be in your 40's around 20 year old's who have completely different ethical, moral, and work ethic than you do? Personally I would rather find/work for a business that have similar cultural values as myself than find a business that have completely differing values. Being at a start-up when you're young, healthy and want to go out with your colleges and get hammer after work is fantastic. Though when you're in your 40's I can see nothing better than finishing work at 5pm, going for a 1 hour jogging with my partner and curling up in bed at 10pm to read a book.
Do I think I will fit into a young crowed who have absolutely no social circles outside of work in their 20's now? The answer is no. Do I get approached by startup's to start some new fancy facebook clone every 2-3 weeks? The answer is 'yes' but I decline their offer's.