I think it's important to reminisce every now and then. Not too often. The past is gone and that's a good thing, ultimately. But just a quick look back, a peek at the view below you, to see where you stood then and where you stand now. It's weird to think of myself even two years ago. I'm not that person anymore, not in the ways that count. I'm not "finished" yet, not by any means, but there are some things about living that I understand now in a way I never used to. There are things I said and did that make me shudder with embarrassment (just as I'm sure I'll wince when I read this after I hit 30).
If I didn't have Very Serious Opinions on the topic of time travel, I'd almost wish I could go back to tell my younger self a few things. Like that adulthood isn't something to be feared or fought. Getting older doesn't mean you have to give up the things you love, and it doesn't mean you have to slow down and get boring - you just have to accept new responsibilities (to yourself and others), learn to be self-reliant (and reliable!) and hold yourself to an ever-higher standard. It's harder, but the rewards are worth it. You learn how to manage real freedom and responsibility, and the essential balance between them.
You get to make choices. Real, big, awesome choices. And each one comes with consequences, with sacrifices, pleasures, freedoms and responsibilities. On some level I always recognized this, but actually feeling it all, the positive along with the negative, is something else. Everything you do has an impact, small or large, on the people and the community around you. Your pleasure may come at the price of another's pain, or your fortune directly from another's expense. And part of being an adult - probably the most important part - is honestly accepting responsibility for the results of your choices. Sometimes that means you have to look at yourself in an ugly light and make some hard decisions about who you are and who you want to be. Sometimes that means having to choose doing what you feel is right over being "nice" or being liked. That decision is yours, and so are the consequences - and you have to own them.
Everyone learns these things at a different rate - some are born into privilege, in a bubble. Others are born into struggle and responsibility from a young age and need to grow quickly just as a matter of survival. I was always pretty fortunate - we weren't rich, but I grew up living in a comfortable zone that a lot of other people don't get. And I'm much further from rich now, but I still automatically benefit every day from a lot of things based solely on what I am: my colour, my gender, my orientation. And in the past (and I'm going back way further than a few years now) it was easy to just live in that bubble and feel like my own little struggles and feelings were big and real and important, but I can't do that anymore. You have to step out of it - even if you can never understand first-hand other peoples' struggles and experiences, you at least have to do your best to try, to be conscious of reality beyond your own perceptions.
Ultimately everyone has to learn this stuff and there are no excuses not to. Right?
I used to have a hard time with change. My biggest, most crippling fear was always rejection. I avoided a lot of risks because of that fear, and as a result often let my life get stagnant. The mere thought of losing people - even "just" acquaintances - was a dull ache I couldn't chase away. I would react to change with deep mourning - even if I kept it hidden inside. I couldn't let go. Like an emotional hoarder. In my mind, people and things in my life had to stay there, purely for my own selfish needs, even if there was nothing left to keep. When people didn't "get" me it felt like a slight, or a personal failing. All of it, eating away at me always.
But now, mostly, I think, I hope, I seem to get and accept that no one thing or person or whatever is made for everyone. People may not enjoy or like who I am or what I do for valid personal reasons that I have no control over, and that's fine. It has no effect on me. It's out of my hands and not worth my energy worrying about. (And at times I may worry about it anyway, but I try to push it aside.)
I've even effectively let people fall out of my life on several occasions. I've abandoned interests, hobbies, mindsets, outright. Not with any malice - it's either because I've realized I have no real connection with them anymore, or because they've had a negative impact on my emotional state and/or sense of well-being that I could no longer accept or justify. And there's nothing wrong with that, at all. Sometimes you outgrow people, things or situations. Or you both grow in separate directions - however you look at it. (Though there are a lot of people I just plain haven't kept in touch with well, which is a different thing entirely.)
And that gnawing feeling? That doesn't really get to me anymore. Because sometimes what comes next, and who you'll be next, is so much better.