A significant factor in PTSD is the guilt one obtains because they believe they have failed somehow, somewhere, in that they now believe they have become weak to obtain such an illness. There is a very good explanation that goes with this, that I believe will help people to see a more appropriate approach to remove their self guilt for obtaining PTSD.

At some time in your life you have most likely cut your finger with a knife. If the blade was blunt then you may have only suffered a little nick. If the blade was sharp, you have have bled all over. If the blade was very sharp, and the force behind it was great enough, then you may have lost an entire finger.

Now... the extent of the injury depends upon the sharpness of the blade and the power behind it, than the toughness of you skin as such. Given enough force, even extremely tough skin would not protect you from teh knife, and anyone else in teh same situation would also be injured, even if they had the toughest skin in the world.

The same holds true on a psychological level. There are events in life that would make almost anyone "bleed all over." It is such events that make people susceptible to PTSD.

So from this you can hopefully see, that regardless how tough you are, there are forces within life that are powerful enough to break the toughest skin, or in the case of PTSD, toughest minds.