I'm betting you and eyeball are over 50, and have never been capable of anything near what has been described here. (I wasn't up to what's been described, but I was close once my mental ability caught up with my physical ability, and that was in my mid 30's - I did some wild things in the mountains)
Someone trained in the SAS or Seals would have no issues. His narrative and his reading of his own condition leads me to believe that he is may have some background along those lines.
