Why does Amir say that Baba dies "on his own terms?"

At the end of the night, Soraya and Amir helped Baba into bed. He refused his morphine, saying, "There is no pain tonight." He died in his sleep. Amir acknowledged that Baba was his obstinate self until the end; he even died "on his own terms." Baba chose how he lived his life and how he ended it. Countless people whom Amir had never seen shook his hand and told him how Baba had helped them in one way or another. As he listened to their remarks, Amir realized that he no longer had Baba to define him or guide him; he felt terribly alone. After the burial, Amir and Soraya walked through the cemetery together and Amir cried at last.