Why did the ancient mariner have to tell his tale to someone?

The Hermit tells the Mariner that he will be physically compelled to share his story from beginning to end. His physical discomfort will be aleved by the telling.

he had been carrying the burden of his guiltfor a very long time,or maybe he was feeling might.leave this world and donot wnat to carry this burden into the world within his heart.so, there was this need to his story to someone so that he could make his exit with alight heart.