Is it just a fact of life that once a human reaches a certain age they begin developing aches and pains in their bodies that never go away?
Does every older adult simply have constant 24/7 pains in their bodies they just learn to live with and work around?
Yes and No
The old joke - Patient: "Doc it hurts when I do this" - Doctor: "Well, don't do that" - is not really a joke.
Take care of yourself as best you can, and then learn to adapt and ignore.
For example after my shoulder surgery I will never be able to shoot a basketball or throw overhand worth a damn. c'est la vie
PS - I get a hamburger and fries at McDonald's once in a blue moon, there really is no substitute