People do outrageous things in the world, and an earlier me might have had a self-righteous anger about it. Today, while I certainly have an intellectual care, I have the luxury of putting such things out of mind and just enjoying my day. I still take proactive steps to better the world where I think it makes sense, but not out any emotional fervor. I save my passions for my family, hobbies, and a subset of professional interests.
I haven't read the book, but from the abstract, I suspect "The Subtle Art of Not Giving a F*ck" by Mark Manson is basically where I arrived. I have learned I have only so my F's to give, and so spend them more wisely.
Not entirely 100% percent the same sentiment, but still a pretty good soundtrack for not handing out Fucks too quickly: https://www.youtube.com/watch?v=Vqbk9cDX0l0
I can echo what he said though and I can tell you I am definitely not depressed. Some things do excite me, some thing do still piss me off. But overall it's definitely less. Good on the getting aggravated 'for no good reason' side. Sort of sad (not in the being depressed way) on the being excited for something side.
E.g. I still have my pet peeves at work that I will passionately talk about or convince you of. I will not get mad at you any longer if you don't change that variable name to exactly the wording I suggested.
I just post this into the void to avoid burdening my family and friends. I should go do the dishes...