My knees. I am past 30, and my knees somehow don’t want to bend anymore.
On the other hand the older I get, the smarter I get about life. Do some physical activity on a regular basis, keep some long term goals in mind, don’t let your emotional state depend on external factors.
Find balance in your life and know your limits and you will be all right.
I was outside on concrete with grass on the side of it and forgot to put the hand brake in. I step off, just to see the truck roll into the grass with the back wheel. Luckily the concrete the truck was on was high enough to stop the truck when one wheel was on the grass.
The truck was stuck now. Driving forward didn’t work, pulling did not work. In the end we pushed a piece of pipe under it with hammers on both sides and that was enough to lift the back of the truck high enough that I could drive it forward again.
Still sucked though. I never forgot the hand brake again. Also did not get fired, that is never really an option for employers here.