I'm in my 40s and I feel very tired. My bones are rattling already, way too early. Migraine once a month. I used to think I'm depressed, but really I'm not, just tired. And soo many of the people I know feel the same! Some put it down to long Covid, some say it's the vaccines, some call it chronic fatigue, some call it other things. But many are tired. And angry, because when I was very young I fought against environmental destruction, grownups told me to stop or go to jail, and look where we are now, while the very same thing is still happening!
For me it's the polycrisis: the knowledge that things are most probably going to get worse for many people before they get better. Like some bad vibe in the background, while one still has to try to survive every day, which gets harder and harder. I'm earning half of what I used to while everything is twice as expensive, go figure. And I'm one of the lucky ones, with a setup that enables me to work less hours than average.
Also someone mentioned CO2 one of these days, and not to forget the heat - that might be why my brain really doesn't work very well anymore.