You can have the same feelings toward pain from physical activity. "Did I strain my shoulder in my workout or did I tear a ligament??" or "Are the ligaments in my foot sore from snowboarding or did I tear my ACL??" I used to be afraid of this kind of thing all the time when I first started being active. My general point is that regular physical activity gives you psychological faith in the resilience of the human body. Having done loads of activities and sports for over a decade now I am much more confident in my body's ability to bounce back from injury than I did when I was more sedentary and every ache and pain filled me with fear.

I think folks are really focusing on the "psychological" part of my comment in isolation and not the "problems of leading a fairly sedentary lifestyle" which is probably my fault because I don't think I structured my post well.

I think a lot of the problems that are associated with aging, such as minor aches and pains, are consequences of leading mostly sedentary lifestyles. Part of being fairly active (meaning well above most state-recommended guidelines) is the psychological resilience to pain that I mentioned. But also part of it is that because you are constantly pushing your physical abilities, the strain that comes from occasional bad movement as part of everyday life (sleeping badly, holding the faucet tap the wrong way, hitting your wrist on the corner of a table, etc) is usually well within the envelope of pushing yourself compared to your actual sport.

My greater point is that leading a sedentary lifestyle is a whole package of things. This includes the physiological consequences of not developing strength, flexibility, and joint elasticity; this also includes the psychological resistance to risk and pain that comes from being sedentary.

I agree with you totally that being physically active is important for being healthy.

And I think there's something to be said for your point that experiencing pain and seeing yourself recover from it can be helpful for processing pain psychologically. You could look at it as sort of exposure therapy for pain.

But I also think that the kinds of pains you get from exercise are quite different from the psychological experience of pain from a serious injury and the former doesn't really prepare you for the latter.

It's hard to explain unless you've been there. Most of the time, pain is a signal from your past telling you about something you did. It's your body's way of saying "don't do that again". But when a severe injury happens, it can also be an omen for your future. Your body saying "no, you don't get to do that anymore".

Processing that is difficult, especially given how uncertain the signal actually is.