There are a number of character traits and principles of Santiago’s which can be adapted to any career. For the purposes of answering this question, I will discuss three: determination, problem solving skills, and the ability to manage stress.
With regard to determination, the fact that Santiago continued to head out to sea even after his apprentice, Manolin, was unable to accompany him any longer for financial reasons, shows real commitment to his profession. He shows himself to be the kind of man who gets the job done no matter how tough the circumstances get.
In terms of problem solving skills, Santiago proves that he is a man with a plan. When he realizes that his marlin is too big to fit into his boat, he simply ties it to the side for the trip back to shore. I’m sure Santiago would be the first to admit that his plan wasn’t foolproof, since his marlin was essentially eaten down to skeletal remains by sharks en route, but the fact remains that Santiago showed great problem-solving skills in bypassing his initial challenge.
With regard to stress management, sitting on a boat for two days fighting with a giant marlin is certainly a stressful situation. However, Santiago kept his wits about him the entire time, remained calm, and did not give up.