You heal slower. MUCH slower. Even dumb shit like a bad scratch on your hand. Itll be a scab for weeks, not a few days.
In subreddit r/AskReddit
In a post titled:
Hey y'all in your 40's: what are the physical changes you start to see in your body once you leave your 30's? What should we expect to experience physiologically as we get into our 4th decade?