Life CAN open up to you when you become an adult. If you have dreams and aspirations, adult life is where you can do those things. You can study things you find interesting, you can travel, you can meet so many different people, you can fall in love, get married, have kids... whatever you want.
If you have depression it can be different, because that sort of stops you enjoying these experiences even if they do happen (in my opinion at least).

I think your thoughts change as you get older. I do believe that you learn what's important, I mean what is REALLY important. You don't sweat the small stuff so much, like if you have a spot on your chin or if your shoes match your jeans. You learn what you like and enjoy and you learn not to take certain things so seriously. You learn that life is too short and that it's worth enjoying while you have the chance.

I'm 25 and the world is open to me, right now I could go anywhere I want (and have done), and I find that so exciting! (well, once my confidence is ok again cos right now it's zero) But... I think the number one thing that's great to learn while you're young is self esteem and confidence, if you have that, I think you have a lot of potential for a great life. And if you don't have those things, they can be learned.

It is true though that you get out of life what you put into it. And you don't really get things if you don't want things, it's good to have dreams and to try to follow them.