The first lesson is to listen and heed warnings. The old man in the story was warned not to go into the Yukon by himself. The temperatures were 50 below zero and nature can be unforgiving. The old man did not listen and ultimately this lead to his death.
The second lesson is to listen and observe the things around you. The old man had opportunities to turn back and save his own life. His spit was freezing, the dog was nervous about continuing and his knife was frozen. Nature kept throwing