For reference, I'm 37 now.<p>First, I wish I didn't take my health for granted.<p>When I was 24 I gained about 40lbs. I had previously been very active, and I quit participating in some physical hobbies that kept me thin & fit.<p>Without paying it much attention, I gained those 40lbs and on and off have struggled with weight throughout my 30s.<p>Second, I wish I had also put a lot of thought into assets vs liabilities and focused on owning assets. It's a much better use of your money, and the time you spent earning that money. I "accidentally" purchased an asset (a bar) when I was 26, so I got lucky here, but I could have done much better.<p>Third, I wish I had been a better partner to some people I dated. I'm good in a lot of ways: I don't lie, cheat, call names, etc. But I'm stingy with my time. I've always been a loner, and it takes a lot of effort for me to act differently. But I believe it could have been worth it.<p>Fourth, and this isn't for everyone: I wish I had enlisted. I was fresh out of high school when 9/11 happened, and I've always regretted not enlisting. But the military and the activities they're involved with are very interesting to me.<p>Overall, it's hard to screw it up too badly, especially if you're asking questions like this one. Optimize for health and financial health and you will potentially save yourself much of the drama and suffering life can bring. Good luck!