BBC News - With one good leg, US veterans climb Mount Kilimanjaro

Have you seen a greater example of mental vigor recently?

I'm sure each amputee goes through his or her own highly individual and personal physical and mental journey. The same goes for those veterans of war.

I wonder where each hiker became a person who didn't give up easily in their life. Was it military training, their peer group, overcoming the loss of a limb? A combination?

What makes people strong?