Despite the boy not being in the story too much, I think he plays an important role in it. The boy helps give the old man hope, both at the beginning of the story and at the end. If it was not for the boy, why would the old man have gone through what he did? I think that the boy motivates the old man with his confidence, and the old man thinks of that and picks himself up.
The first example of this is before the old man even hooks his huge fish. Before the old man and the boy start talking, the tone is very gloomy and depressing. When the old man and the boy get to talking, the tone starts to get brighter. It even says "His hope and his confidence had never gone. But now they were freshening as when the breeze rises." (Hemingway 13). The boy and his optomism make the old man more optomistic as well, and so the old man is hopeful when he goes out fishing the next morning (Hemingway 18).
Another example is when the fish is jumping and the line is cutting the old man's hands. The old man thinks that if the boy were with him he would help, and after that thinks of how good it was that the fish jumped and that his hands were not really so bad (Hemingway 42). I do not think it is just a coincidence that the old man is more optomistic after thinking about the boy. I think that thinking about the boy made the change in attitude.
My last example is after the old man gets back home. The first thing the old man says is "they beat me," but by the end of the book, the old man is making plans to go fishing again (Hemingway 58-59). The boy's confidence in the old man helps give the old man more confidence in himself. Because of this, the old man is able to keep going and endure what he must even when things go badly.
Hemingway, Ernest. The Old Man and the Sea. New York: Scribner, 2003. Print.