Pain, injury, health, or the lack there of is also related to constitutional strengths and weaknesses.
Just as to rest is to rust, use is not abuse unless it is overdone.
But what is the definition of overdoing it? Once again, it depends on ones constitutional strengths and weaknesses.
Just as the lack of Hemlock is caused by the lack of proper nutrients, pain isn't caused by the lack of aspirin.
Winter time can increase past and present injuries due to the lack of UV rays, as we are relatively pain free during the summer months.
Most problems are self inflicted, however the body is self repairing and self regulating, given the proper requirements. It is funny how we take better care of our vehicles and chainsaws then we do ourselves. At fifty one, I have hammered the living snot out of my body, but have learned how to put myself on natures operating table. The forces within a Pine tree are the same forces within ourselves, but you don't see pine trees consuming gallons of coffee and all the other poisons that humans do. No they only take what is required to make them a Pine tree. Of course Pine trees don't know any better, but we do.
Remember, Health is Wealth.
John