Lots of things like grey hair, moving more slowly, injuries that I would have bounced away from before instead hurting for weeks or months.
But the one that hit hardest was a breakup I had a little while back. She was the love of my life and I fully intended to marry her, and when she ended it out of nowhere I was sad, but fine. She dumped me, and it sucked, but I also needed to finish a staff report for a Planning and Zoning Commission meeting that night. So I moved on.
The thing that upset me most was that I wasn't that upset. There was a time in my life when I would have been a mess. But as I've aged, my emotions have become more regulated.
I miss being capable of that level of joy and pain.