While people are in the military they learn a particular way of dealing with pain.
"Pain is weakness leaving the body."
That helps keep them effective as soldiers while in physical pain; reciting that mantra they focus on being strong - on continuing to do their duty - and doing that takes their minds off the pain. Doesn't make it stop hurting, but allows them to think about something else for the duration of the emergency (or until they get killed, whichever happens first).
It keeps them effective as soldiers, but it makes them about a thousand percent more prone to further injuring themselves than people who haven't been through that. And it leaves them prone to re-injuring themselves by stressing parts of the body that aren't fully healed.
I've heard that mantra dozens of times now from guys who are out of the service for years and still in emotional pain, and as a long-term strategy for dealing with emotional pain it sucks, for pretty much the same reason it isn't an effective long-term strategy for dealing with physical pain.
In my not-so-humble opinion, the military organizations of the world should devote at least as much effort training ex-soldiers to be effective civilians as they spend training ex-civilians to be effective soldiers. Most of them Don't. To be fair lots of countries have something like the (USA) GI bill that covers college tuition for ex-soldiers, but most of them don't, and even the ones that do don't devote effort to the emotional side of it.