Duty and honor.
Haoyou knows what to do when he sees his father bravely facing death in the face of adversity. He does what his father did, facing the storm head on, until his ability to deal with nature makes him famous. He is the suffering one. This is honorable, because in light of human tragedy and suffering—the wrongful death of his own father even—Haoyou continues on his quest in a dutiful manner.
Reward and meaning.
Ultimately, Haoyou's journey is not done for the sake of reward, but he does benefit from his integrity. For instance, he is good enough at his father's job to earn the prestigious approval of powerful men—even Kublai Khan. His life is rich and meaningful, and that doesn't make his situation better, but it makes his character better. Still, even without 'meaning' per say, life is worth it.
"Weathering the storm."
The main question of the novel seems to be, "Is it worth it to weather the storm?" Perhaps a better question might be, which of the characters in the novel are evil? It's the ones who take the easy way out. The ones who lack integrity. But by being refined by the harsh reality of nature, Haoyou is made into a powerful, respectable person.
