I turned 35 last week. No crisis to report.
I expected the milestone to feel more significant than it does. It doesn't, particularly. Life continues in its usual way: some things working, others not, most of it in-between.
A few things have clarified, though.
Energy is the real resource. Time management assumes the constraint is hours. It isn't, or it isn't only. The constraint is attention and energy, which are finite and non-renewable within a day. I've stopped filling every hour and started protecting the hours where I'm actually capable of good work.
Most urgency is invented. Very little that feels urgent at 9am will matter by 9pm. I've become much slower to respond and much less apologetic about it. The things that are genuinely urgent make themselves clear.
The friends you see regularly are the friends you have. Proximity turned out to be load-bearing in a way I didn't appreciate in my twenties. I've made more effort to be physically present with people I care about rather than maintaining friendships through occasional messages.
Health is annoyingly foundational. Sleep, movement, eating reasonably well — I've known this for years but I've stopped thinking of it as discipline and started thinking of it as maintenance. You maintain the machinery or the machinery starts to let you down.
None of this is original. I suspect wisdom is mostly just things you already knew, finally taken seriously.