Dad has lung cancer and feels that he doesn't care much about him at ordinary times. What should I do if he is too sad because he has been delayed?

Now is not the time to be sad. Now you can't be sad in front of him, it will affect his mood too much. Although lung cancer has the highest mortality rate, there are always a few exceptions, in case he is the lucky one. In other words, no matter how long he has left, let's spend some time with him and see what he wants to accomplish. The incidence of lung cancer is very high now. Nobody wants to stand on it, right? Give him whatever he wants to eat. Do your best, okay?