The will to survive is always a dominant factor. This is something you would have to ask Doug Ritter about as he is somewhat more knowlegeable this than I am. I can tell you that there are documented case's of reasonably equipped people, who should have survived, dying because they have perceived their situation as hopeless and basically given up. Other people have who should have died because they went out with nothing, survived. Purely because they have decided that they ain't going to die. And gone from there.