Final answer:
Baba tells Amir that he must rely on himself, using his will and self-control to navigate life's challenges after Baba is gone.
Step-by-step explanation:
When Baba is diagnosed with lung cancer and Amir expresses uncertainty about what to do without him, Baba's response to Amir emphasizes self-reliance. He tells Amir that no one but himself can help him out of it, encouraging him to use his will and self-control and not to succumb to silly fancies. This pivotal moment reinforces the themes of personal growth and the necessity of facing life's challenges independently within the narrative.