My brother is doing the same trek next year, and he is a slob, so I sent him the outcome of these two who were walking 150klm/week with packs for training, but looking at the bloggs last night, some on there suggested some sort of simulated high altitude training was avail like an inverse hyperbaric chamber? My guys didn't do that or perhaps even know about it. I think also that we would all react differently and even the best level of fitness might not get you there if you can't stand the lack of oxygen, plus couple that with picking up bugs etc, all downhill from there. My brother did walked the Kokoda trail a couple of years ago, trained like crazy and it still almost killed him from the heat fatigue and exhaustion, so will wait and see how he fares - hopefully better than these two.