Powerful writing often results when you submit your character to difficult internal conflict. One such conflict is the opposition of what they want versus what they need. Exploring these two ideas tells the reader a great deal about what motivates your character. In the case of your protagonist, it also provides an engine for your story. Why is your character doing what he's doing? What does he want? What does he need? Are they related?
Another thought: How does the difference between want and need change the nature of your character's motivation? Which is the greater motivator of the two? The potential loss of either provides a great basis for conflict and dramatic storytelling, but when a character is forced to give up one for the other, the drama can be almost unbearable.