I'm almost 40 and I've noticed that if I don't get off every day, my sex drive decreases, my erections aren't as rock hard, I don't precum nearly as much, and I don't last very long once I get going.
I've been working a lot of overtime over the last two years and I've gone a week without cumming a few times, and each time it took a week of jerking and edging daily before it was back to getting, and staying, rock hard without effort.
I went two weeks without cumming recently and it was a disaster. Nothing turned me on, not even my favorite porn, I couldn't stay hard for a hook-up (we've been friends with benefits for years, so she was very kind about it thankfully), and it was almost impossible to get myself off, which had never happened before. I saw my doctor and he said my T was high for my age and that there were no discernible reasons why I should have occasional ED, and perhaps it was stress related.
I jerked off every day for a week even when I didn't want to, and I was good to go again, even with my fuck buddy. So now no matter how busy I am, I make sure to play with my dick every day and I've had no issues.
As they say, use it or lose it.