I think his mental resilience and preparedness was likely the key to his survival.
Also, while I'm not religious, I'd guess his faith likely helped him psychologically.
There's a lot of discussion about skills, gear, etc. in bushcraft circles, but the psychological aspects of being remote and/or alone is a far bigger issue IMO.
And yet there's not a whole lot of discussion about it, probably because it's actually one of the most difficult aspects to understand and discuss.
The only way IMO we can really understand the psychology, and develop psychological resilience, is to experience the ups and downs, the fear, the panic, the loneliness etc. and push through them.
Then when we face psychological (and physical) battles in the future we can be more confident that we can get past them, because we know we have in the past.
It's not easy to learn that stuff from the web, or from discussions with people.
Most of the time when something serious goes wrong we should still be able to survive, so long as we can avoid panic, stay calm, and think clearly.
But that's not always easy to do.
I saw a doco on this a couple of weeks ago. Unreal! Especially 12 days without water. I told a bloke at work about it & he said 'nah, you can only last three days', which is what most of us have been told. But the human body surprises us yet again.
I reckon you're dead right LC, resilience can only be built by training & testing yourself under at least similar conditions.
While I think that's probably still a fairly good guideline, people seem to mistakenly treat those types of guidelines as unbreakable rules. And that's a problematic way of interpreting them.
Thinking you can only last 3 days is likely to increase stress levels and make you use up your water faster. So that guideline, if interpreted as an unbreakable rule, could even be detrimental.
If you know you could possibly go for 12 days then you might have lower stress levels, and better conserve your water.
That's where psychology has a direct impact on physiology. In an obvious way, because stress affects the body (making your heart beat faster, and sweat more, etc.). But also likely in a whole lot of other ways we don't understand.
Another issue though with dehydration is potential brain damage. Even if you survive for more than a few days without water there might be lasting damage.
I've had an afternoon without water (not even a whole day), exerting a lot of energy, sweating like crazy, and that evening through the next day (even after getting water) I was feeling sick.
I can't imagine going 12 days without water while exerting a lot of energy, especially in the desert. I at least had shade to rest in.
Admittedly I was unfit at the time so I was sweating more than when I'm in shape. When I'm fitter I'd probably cope better.
I've done 5 days without food and after the first 3 or so days it's actually surprisingly easy. I could have gone longer but I wanted to have a few beers and I can't drink without eating, so I ended the fast.
However that fast was done while I was sitting around at home much of the time, watching docos, movies, etc.
I can't imagine having to walk a long distance, in the heat, while not having food.
But the body and mind can adapt to do amazing things if we condition them. That conditioning is the key.