This idiom may come from Zhuge Liang's Book of Commandments during the Three Kingdoms period. In the Commandment, Zhuge Liang wrote: "The patient is becoming more and more suspicious when he meets a dark ghost. Suspicion gives birth to dark ghosts, which makes his condition worse. " This means that the patient is not healthy, and if he suspects that he has a dark ghost, his condition will get worse.
Therefore, this idiom means to remind people to keep a healthy attitude and avoid excessive doubt and worry, so as not to have a negative impact on the body.
Solemnly declare: the answer is for reference only, please don't be blindly superstitious.