> I increasingly wish I could go back to my 20s. Now I feel too old to go to festivals, bars and clubs and make new friends that way.

I'm 40, and I guarantee you are not too old for things. If you used to meet new people in bars, you still can. No, you shouldn't go to bars that are predominately people in their early 20s. Find bars (and other venues) that tend to attract a crowd closer to your age. As much as I dislike meetup.com, resources like that can help you find people who like to do the things you like to do, and can introduce you to new things if you're willing to take a leap.

I will admit that the pool of people is probably smaller. People pair off and start families as they get older. Even if they only pair off, couples probably "go out" less often than single people. But also consider that people are getting married later and starting families later these days. So there are still likely plenty of people out and about who share your values and likes.

> I feel like I've seen most things before, and it's all just different iterations of the same.

To some extent that's true, probably. But maybe that means you need some new hobbies. I assume by your "excited about new technologies" line that you're a software developer or similar. I, too, play around with tech as a hobby in addition to my job, but make sure you're branching out and doing other things that have nothing to do with tech.

> I am single and haven't had a serious relationship for many years now.

Don't put too much pressure on yourself, or attach too many expectations to this, as that will have the opposite effect. If you're having trouble meeting people, try dating apps. They're far from perfect, but they help you get out there, and help you meet new people without having the stress of (for example) making a cold approach in a bar or something. Even if you don't find a long-term relationship on the apps, you may find it builds your confidence and helps you get back into the groove of meeting people.

> When I was ~30 I still considered myself young and able to do anything I could do when I was in my 20s. But not anymore now. I feel like my time for everything is running out. Have you been through a similar thing? How did you deal with it?

When I turned 30, I remember the 6 months or so leading up to it were a little stressful for me. The idea of leaving my 20s made me feel like I was "getting old", and I started cataloging what I'd done, and worried that it wasn't enough. But then I turned 30, and realized nothing special happened during that transition. I was still the same person, and I could still do what I wanted to do. Turning 40 last summer was similar. Sure, I'm realizing some things have changed: my body is aging, and I get injured (and take longer to heal) than I used to. I can't drink like I used to without consequences the next day. But I'm still me. I can still hang out with my friends, even those who have kids now. I can still invite people over for dinner. I can still go to bars with friends to catch up over beer or cocktails. I can still go out to restaurants. I can still go out to my favorite karaoke bar and have a wild night, as long as I don't do it too often (well, ok, haven't done that since the lull before COVID delta, and between delta and omicron).

You're turning 35, and even if you die somewhat on the young side, you're only a little more than a quarter of the way through your adult life. You have plenty of time to learn new things, develop new hobbies, further your career, meet new people, find a significant other, etc. While you need to try not to put crushing pressure on yourself to achieve these things, you also need to just get out and keep doing stuff that gives you the opportunity to accomplish these things.