What was hard for Jack to do during the hunt?

This depends on which hunt or where in the story you are referring to. Initially, when they see the small pig in the forest, Jack has a chance to stab it. Jack, however, can't, "Because of the enormity of the knife descending and cutting into living flesh; because of the unbearable blood."Jack had never taken a life before. Killing will become easier as the book progresses. He figures out how to make the spears stick into the pig and begins to relish in the kill.