In The Old Man and the Sea, what does Santiago remember to get his confidence back?
As he fights the marlin into the second day, Santiago has to call on all his acquired ability to stay focused and not lose strength. He recalls a game of arm-wrestling he played in his youth, when he was much stronger, which resulted in his being named "The Champion" by the people of Casablanca:
As the sun set he remembered, to give himself more confidence, the time in the tavern at Casablanca when he had played the hand game... The match had started on a Sunday morning and ended on a Monday morning.
(Hemingway, The Old Man and the Sea, Google Books)
Santiago's opponent is a great athlete and strong worker in the harbor, and the odds are greatly against Santiago. The match lasts for a full day and ends when Santiago, in a burst of energy, wins the match. This memory helps to restore his confidence in his abilities, and he knows that as long as he holds out and does not try to force the marlin, he will be successful.