This one is a simple realization most people will have to face after something that could've been avoided happens... or if you are lucky, when you caught it on time.
It's simple. Many, many times that small, annoying but ignorable pain is a warning of the body telling you that something is wrong, if you choose to ignore it (as many has done) it can move into something big and disruptive... and worse, sometimes irreversible.
Friends, please go to a specialist the moment an annoying pain shows up, specially in the articulations, no matter how small it is. If you know a good physiotherapists, know that this person is going to be your fucking guardian angel.
Seriously, while some may man up a shoulder or knee early problems, even the manliest of men will cry like a baby when the real crap unleashes and his only options are a lifetime of painkillers (with all its implications) and/or extensive surgeries that will not restore what was lost.
It's a shame we really don't have any good ways to teach such essential knowledge to the people, and we usually have to learn it the hard way... or too late.