Odoreater has it right. You have a pretty care-free life in HS. As you go on in life many things become way better but that comes with the trade-off of having more responsibility.
In high school I spent my time hanging out with friends, hanging out with and having a lot of sex with my girl-friend (ahh, the memories of a gf up for about anything, if you know what I mean), at my part time job earning some cash, and in school. I liked all of it. It was fun. But if I didn't have that job it wouldn't have been the end of the world. My responsibilities consisted of doing what I said I would, going to school, and being home by curfew.
College was better in that I had more freedome. But I also had to have a job. Had to to pay for my part of school. All else was basically the same.
Grad school was serious stress, but was pretty easy, if financially poor, living. In a way there was less freedom because of the lack of money, but I got a whole new level of respect from people. Much less sex, unfortunately.
Now that I'm graduated and have a job it's great. I have plenty of money, have a job I like, and am engaged. But if things go wrong I still have to come up with the rent check. Much more freedom, much more responsibility.
It's all about trade-offs. If you look back on your life and you've never progressed beyond HS (and I knew guys like this) then things have gone drastically wrong.