What is your limit?

As I continue to read, the question that comes to mind is, what is your limit? The men in the book are being pushed to continue on a journey where the end is not in sight. They have been knocked off course and have been about 90 miles out, only to find out they were pushed off course and went miles off track. They have gone 5 days with no sleep, and if they have caught some sleep, it was sitting up in poor conditions next to someone to hope to stay warm, they have been at the end of their ration of food causing Ordes-Lees to pass out, and they have been on the brink of death dealing with frost bite and poor circulation. As a human being, the men have overcame more than the human mind allows. How do we know what are limits are? Some people think that working 15 hours a day is their limit, some go sky diving and are risk takers, others see every doctor possible, but when put into a situation with no foreseeable outcome, how far would you allow yourself to go? Could you sit on a floe, and watch as it breaks beneath you? Could you travel on a ship that has below freezing temperatures? I'm guilty as a person, to think I'm loosing my mind walking to my car at 5am in the winter months, shivering as though I won't make it. I couldn't imagine being stuck on a boat in the ocean for 497 days without seeing land. How do you convince your mind that your body is more capable than what you think? The men seem to be conquering fears, will their ever be a point they stop?