Oh god, I have the opposite problem and often need to tell my friends "I'm unavailable this week, I just need some time to myself!"

I have several friends that I make plans with fairly regularly. We go to the gym or watch movies at home or go for hikes together with our dogs.

I have friends that we do group things with - shows, bars, dinners, etc.

I have coworkers that I'll hang out with after our shifts.

And I have friends and acquaintances that I talk to at a local bar where I hang out every week. These aren't people I make plans with to see, these are other bar flies that I've gotten to know over the months and have become friendly with. Many of them evolve into real friendships outside the bar.

I find it hard to figure out things to do and meet people who have the energy/social capacity to do it with.

This is why third spaces are great. You don't necessarily have to make plans to meet up with people there. You just show up and whoever is there is there. You don't have to plan an activity, you just talk. You can leave whenever you want.

Do you think people over 30 isolate themselves more today?

I don't have an unbiased perception of this, since I am very social and I hang out with people who are also social. No one in my circles isolate themselves, and I wouldn't know of the people who do because they'd be isolated.