I'll start by flipping your question to the things I'm incredibly happy I did when I was younger. Which are all sorts of "bucket list" items which are best done

I'll start by flipping your question to the things I'm incredibly happy I did when I was younger. Which are all sorts of "bucket list" items which are best done while young. Aging in your 30s sneaks up on you. At 30 you can still go to the 2am punk rock show and then merely complain a bit more about hangovers getting worse. At 40 you're the weird adult hanging out with people who could be your kid. At 30 you can drop everything and go hike the Appalachian trail for 6 months, at 40 you might have medical issues that prevent this, or kids, or just a general change in outlook such that hiking all day to sleep on the ground sounds miserable instead of fulfilling. My advice would be, if you want to go sail the south Pacific or climb the Himalayas or backpack around Europe or volunteer in a developing country or play in a band at SXSW, go do it now. I'm glad I went and did things while I could, and while I was the right age to enjoy them fully. I've still got plenty more living to do, but I recognize many experiences will never be the same as having done them younger.