Dude puts on a wetsuit and goes kayaking in the winter. But, there is a vast difference in cold and active, and cold and sitting around camp. Many layers and a thick jacket did not help him sitting in camp eating dinner, before the temps dropped. I offered to him that I would pack up and we would hike back to the car before midnight, even. He refused to go. Wanted to see what it was like.

This is where I am going to refer back to the futility of expecting mental toughness to be all you need to be a backpacker. You need a lot more than that. More important to understand the gear you need, how to use it, and recognize your physical limits. I would argue this guy is pretty tough - yet he lacked the physical conditioning to do miles on trail with a backpack, and he lacks some metabolic regulation that would help him stay warm. He stuck it out for the night because that was his goal, and he says he learned a lot from the trip and is actually thankful that I took him. But he is frustrated with himself for not being able to do it comfortably.

It's really difficult to struggle with medical issues that keep you from doing what you want to do, or things you used to do that seemed so easy then....