I'm in my mid-30's, but some "old man" stuff has been creeping in for some time now.
The aforementioned micturation syncopy about got me out a couple times in my late 20's. Both times I was able to semi-controlled-fall onto the ground before actually blacking out, and fortunately both times in my home rather than a public restroom. Both times I had jumped up from laying down to run upstairs to the bathroom.
Actually blacked out once a couple years ago. Jumped out of bed right out of sleep to investigate a noise, found it to be my wife up with the baby, and as I turned around to go to bed I started going out. Managed to direct my momentum in the general direction of the couch as I blacked out, so fortunately I avoided any contusions.
The "old man hairs" have begun. Out the top of my ear, the crazy eyebrow hairs, etc.
Assorted aches and pains. Lower back pain. Developing a repetitive stress injury in my mousing fingers from work.
Haven't been cut up too much yet, though had my gallbladder (possibly needlessly) removed last year.
Just getting started, I guess . . .