To be fair, I've watched a lot of people on the brink of death. (I was a paramedic for a time.) You could often tell the ones that would die despite very similar presentation to one's that would live. The difference was the ones that would live had fight in their eyes. You see that too with folks waiting for a loved one to get there before they die. They can push it back for hours or even days if they've got the fight to do it. They even teach that to rescuers in search and rescue: often people that have hung in for days fighting to survive see their rescue and then they relax and start going downhill fast.

Long story short, there definitely is something to your mental game in a situation like this.

It's a smaller effect than the others, but it's there.