Anecdotally I’ve felt this shift over the past few years. I am 33 and have always been a huge proponent of personal growth, change, pushing yourself to be better. In the past few years Ive felt the opposite urge, an urge to accept myself, flaws and all, as the hand I’ve been dealt and I must merely play that hand, not focus so much on what-ifs, etc. Perhaps this is my brain solidifying.

29 and feeling the same. It's kind frustrating and freeing at the same time. I feel like I'm making less progress, but at the same time don't feel the pressure to make progress.

There is wisdom both in trying to change what you can, and realizing that you maybe can't change everything. If you've been trying to change things, by 33 you may have a fair idea of what you in fact cannot change.

I'd also like to add anecdotally that a lot of people develop burnout at that age, probably because they keep pushing themselves and/or get sucked into their own enthusiasm / passion instead of set limits and the like. But then, I also think people get less resilient to stress and the like after 30, less able to compartimentalize or bounce back quickly.

What you end up getting is people ~10 years into an exciting career where suddenly they can't perform or cope as well as they used to. But they can also be in a pretty senior position by then and be pushed out of their comfort zone.