When it comes to trauma, I see it like jumping out of an airplane: if you don't have a parachute and you land on the ground, you're going to get broken legs and all sorts of messed up things if you survive. That's what trauma is like. There's very little you can do to stop yourself from being traumatized by something.
I think the best chance we have at preventing ongoing issues is to try to adjust the culture of coming forward for help so that people can learn how to self-assess: “I'm going through a stressful experience; I'll get assistance for it right away, take some downtime, get some time off.”
If it can become a cultural norm that getting injured psychologically overseas is no big deal, that it's just something that takes some downtime to recover from, then that's probably our best bet to preventing the ongoing issues that we start to see now in our veteran populations as they move out.