Yang Qing lost himself to the wondrous state of contemplation. One of the guiding motivations as to why he was so diligent in his cultivation was to grow his strength so he wouldn't end up dying as some fodder somewhere without any idea of how he died. His greed wasn't just towards food and treasures, but for his life too, and when it came down to it, life took precedence over all the rest.
Fear of dying was what kept him diligent and persistent in his efforts, but it wasn't the only thing that kept him going. Unbridled curiosity and fascination were also compelling factors.
If immortality did exist, and by luck, he managed to reach that realm, fear and the desperate need to grow his strength would cease to be a factor in whether he continued cultivating or not, or diligently at that.