Sometime relatable

It's probably related to doing literally nothing.

Well now I feel personally attacked
- Yup, I've started working out specifically so getting older sucks less.

This is a character inside everyone and it's like a level boss .... the more years pass, the bigger the pain level boss ... you can easily beat the early bosses but eventually they get harder and harder to fight until eventually the pain boss kills you.

Is this a thing even for people who get regular exercise?
- Yes, everybody grows old.
- I'm almost 50 and even with regular exercise ... things are still not easy. You have to maintain a certain level of activity and if you just get off one or two days, it will take you a week to jump back to the same level again. A year ago, I got excited and went running around with my little nieces and nephews for a game of lazer tag. I did shuttle running without thinking for about an hour. I thought I did great, everyone thought I was in great shape and an athlete ... I felt like I was 18 again. I couldn't move out of bed the next morning and my muscles cramped up for two or three days after ... it took me a couple of weeks to get back to normal. Enjoy what you have ... the end, beginning of the end or the ending is closer than you think.
- At around level 40 - 45, if you haven't prepared for it, the Pain Bosses can really affect your level of playing.

Except it does correlate meaningfully, don't believe me? Break your index finger, does it hurt? No shit.
That's not to say the nervous system can't create pain that has no source, the entire condition of fibromyalgia is evidence of that possibility, but to say they aren't meaningfully correlated is insane.
Most people who have pain unrelated to medical diagnosis in their 30's and 40's are fat as hell, eat like crap, and get no exercise, and are constantly dehydrated. That's why they hurt so damn much.