Character Analysis
The boy is kind of a jerk. (Hey, someone had to say it.) Sure, he starts out loving the tree with all kinds of childlike wonder, but as time passes, he takes just about everything from her without so much as a "thank you."
Each time he returns to the tree to ask for something new, we see his selfishness in action. He doesn't appear to care how his needs, and the things he takes from the tree to meet them, affect his childhood friend and confidant. Nor does he seem to fully realize that despite these attempts, happiness continues to elude him.
When he first returns to the tree as a young man, the boy asks for money because he wants "to buy things and have fun" (36). His next request some years later is for a house (41) and after that for "a boat that will take me far away from here" (46). Each time, the tree complies with his requests and suggests that perhaps now the boy will be happy.
But he never is. And the request for a boat so he can sail "far away from here" (46) is a big clue that instead of taking responsibility and facing up to the challenges of his life, he's running away from them.
In the end, the boy does appear to have gained some wisdom. During his final visit to the tree, he says, "I don't need much now, just a quiet place to sit and rest" (54). He seems to have realized that his constant search for happiness has been in vain and that material possessions, while they may have provided him with comfort, haven't led to fulfillment.
So, in his old age, he returns to the place where he was happy as a child. And, finally, he is content to simply sit down with the tree and be thankful for what he has. Or maybe, as he says, he's just tired. Perhaps he hasn't learned a thing. Just like with the tree, your interpretation of how the boy has grown and changed will have a lot to do with your overall interpretation of the story.
In the end, when the tree tells the boy to sit down and rest, the boy does. The question you need to answer is whether he does so out of wisdom, resignation, a continued lack of respect for the tree, or just plain, old complacency.