I'm noticing the following:

Random injuries happen more frequently and take longer to recover. I'll sleep on my neck wrong, run into a wall or my arm will get yanked by a kid, and it will hurt for a few days rather than a few hours. Things like that.
Recovery time from injuries takes longer. I have weak ankles and if I tweak it, it will take twice as long to get back to 100% then it did before.

I am not finding a decrease in my endurance - my times compared to say my 20s are consistent to go along with the amount of training I'm doing.

I've also started doing a lot more pull-ups and push-ups after hearing some here on CB talk about it. I probably have better muscle definition now than my whole life. Of course runners are usually deathly skinny, so the bar has been set pretty low there.