What is Santiago's attitude in The Old Man and the Sea?

In The Old Man and the Sea, Ernest Hemingway presents an elderly fisherman who is both attuned to the natural world, having spent most of his life fishing in the open sea, and determined to wrest a living out of this dangerous environment. Santiago is both optimistic and stubborn in staying out in his boat long after it seems he has no chance of catching any fish. Once he hooks the marlin, this tenacity turns to obsession, as the sharks literally consume the fish and the impossible situation figuratively consumes his sanity. Out in the boat, not catching any fish for weeks, he starts to get distracted and then corrects himself, "now is the time to think of only one thing. That which I was born for. There might be a big one around that school, he thought."
When he realizes the huge marlin is within his reach, his strategy depends on respecting the fish and understanding its psychology:

He is a great fish and I must convince him, he thought. I must never let him learn his strength nor what he could do if he made his run.