Probably a bit of a strange question, but watching Cody Lundin on Dual Survival has got me thinking. Cody manages to go barefoot in just about every climate short of arctic, and even in deep snow he only wears wool socks. At various points in the show he said that he wouldn't advise most people to do what he does as he's been doing it for years, and also says that through his acclimatisation his mitochondria have become far better at generating heat to allow his feet to deal with cold conditions. Assuming Cody isn't just a genetic freak, is there much knowledge on just how much the body can acclimatise to harsh conditions, and just how quick/slow the process is?