It made me question reality in a way I hadn't before.
Is all of this pre-determined? Is it arbitrary? Is it random? Is there an underlying meaning here we should recognize?
I came to believe that love, connection, existing itself, were all somehow significant. Hard to say if this is real, or just part of the pattern :)
This journey has greatly increased my ability to feel compassion for all people, even people that I think are acting unkindly and doing great damage in the world.
Just for grins, here's a YouTube channel that I think you might enjoy:
https://www.youtube.com/c/SamaneriJayasara
I get chills when I listen to her version of the Bloodstream Sermon, too:
Sam Harris, while I never followed his meditation talk much, had one example recently that really drove home the "can't predict thought" concept. Something like "think of a song, any song", and then he challenged you to think about why you picked that song, and not one of the other songs you know. And then, despite whatever explanation you concoct, think about all the songs it didn't even occur to you to choose that fit the same criteria. It's kind of magical.
I do think all this can make us more tolerant towards other people, but it's still a bit circular. If it's all meat and electrons, they're destined to commit the crime, and we're destined to lock them up. (edit: I mean: if they commit the crime, you can't blame them, and if someone jails them, you also can't blame them)
As far as I know, the trend is that older people tend to mellow out - usually! And I think that having a sudden realization that you're not so in-control can be tough. It can catch you off guard if the time isn't right. But after a few years, hopefully people course-correct a bit and start to give themselves more buffer and steer away from activities that exacerbate those anxieties. Or at the very least, one may become more numb to it as the novelty wears off.
I'm not much into meditation but I have had experiences that viscerally proved to me that I am not in full control of my actions.
In my late teens and early 20's I developed a social anxiety, paruresis, which made it impossible for me to urinate in the presence of strangers. I could stand at a urinal, I could will myself to go as much as I wanted, nothing would happen. It felt very much like being a passenger in my own body. Happily, I was able to use graduated exposure therapy to make this manageable.
With kids I've also seen a lot of storymaking. A child will have an impulse to do something and when you ask them why, they don't know but they make up a story for it. I strongly believe we all do this. We act on impulse and then tell ourselves stories to explain our motivations and maintain a coherent sense of self.
Back in the early 2000's researchers were doing experiments on rats to remote control them via brain stimulation https://www.scientificamerican.com/article/researchers-guide...
The ethical aspects aside, my intuition is that if you wired up a human being with something similar you could remote control them to go left, right, forward or back. Afterwards you could ask them about their behaviour and they would explain it with a story in terms of their own free choices and decisions.
We already know this to be true: Advertising.
I suppose the most profound aspect is realizing that you aren't who or what you thought you were. Your free will is a facade, and it can feel unsettling.
I try to see the silver linings, like you mentioned. The first time I heard someone nail this on the head after quite a long time of sensing it, but not understanding it, was Sam Harris. I know many others have talked about this phenomenon and perhaps they've done it better, but he helped me understand it and feel better about it quite a lot. It was very unexpected, too – until that point, I'd never really listened to him.
He advocates a lot for forgiving others on account of this lack of free will, which I really like. It's maybe the brightest silver lining. I find it easier than ever in my life to let things be when it comes to external matters. I'm a lot more compassionate towards people I may have only been bothered by in the past. It's easy to get into a headspace in which I see myself in people, and recognize how I never intend to be wrong, or bad, or whatever – and that's likely no different for them.
I sometimes miss living in the facade. At the risk of sounding dramatic, I don't know who or what I am anymore. It was nice not having to consider it before. Sometimes I can't help thinking about the cellular activity and electrical signals in my body, apparently generating whatever this life is, whatever I am. It can interfere with every day life even. It can be sort of disassociating almost. I think a significant challenge going into my 40s will be finding a way to not care about these things and just let them be, and to focus on making the most of things.