At 67, here's what I've found.
Injuries are a constant problem. They come more often and leave slower.
Healing takes longer, whether it's a paper cut or a hamstring pull.
Warm ups are a pain. I warm up like an old man... 12 minute mile pace and even that hurts with every step... not exaggerating... it hurts with every freaking step!!!@ It goes away after 15 minutes and some dynamic drills.
The above problems make it harder to stay motivated.
The emotional ups and downs of life are less pronounced. You don't laugh as much or cry as much. It's hormone related, but somewhat within your control. You just have to fight the urge to just zombie out at times and force yourself to do fun things.
Sleep seems about the same. I still need 8 hours.
Cold weather hurts... as in physical pain. I ran all winter in Omaha in 10-20 degree weather in my youth, but now when the temp drops below 40, I'm miserable. I'm even cold indoors in winter!
One bright side. Largely due to being a lifetime runner, I never noticed aging until after age 58. Sure, my times were slower, but I didn't notice anything else being different due to my age.