I was having a chat about being in your 30s last night with a new friend, and we both agreed that 30 is so much better than 20. Sure, when you're 20 you get to mess around and have relatively few responsibilities. I mean, I had fun when I was 20, but it was also kind of crazy. When you're 20 you make lots of mistakes. By the time you're 30, you've learned how to avoid making most of those mistakes again.
When you're 30, you know what qualities you appreciate in others and can easily spot those qualities in people. You waste a lot less time on people who don't have any of the things you like in a person. You know so much more about how you react in certain situations. You have a better understanding of where you fit into the world. You can find your people and your places more easily. Your choices are more informed because most of the time you actually have past experiences to draw upon for reference.
Yeah, maybe my back problems are getting worse, but it's okay. I'm having a pretty great time being 30. (Though maybe you should ask me about this again in 6 months. I've only been 30 for about 2 weeks.)