How did Zhuge Liang predict that he would not live long?

First of all, I want to say that gossip and astrology have no scientific basis. And Zhuge Liang will not have the kind of foresight described in the Romance. Predicting death written in the romance is just a way to exaggerate Zhuge Liang's ability, which contains the author's superstitious color.

If Zhuge Liang really predicted that he would die within seven days, it was from his physical condition. People can feel how long their life span is from their physical condition. Therefore, please don't believe too much in the words created because of artistic needs.