Why is it difficult to achieve unity of knowledge and action? This is mainly due to a lack of profound understanding of the consequences brought about by action. Everyone knows that drug use and smoking are harmful to health, yet very few people quit because of this knowledge; it's because they haven't felt the benefits of quitting. In other words, they haven't deeply realized the consequences of not quitting. Life has a certain ability to adapt to the environment, and living in the moment is a natural instinct. Most people do not consider long-term consequences; only when the negative outcomes approach them do they feel a sense of crisis, but by then it is too late, as many aspects of life do not allow for trial and error. There are also some things that allow for many opportunities for trial and error. After continuously experiencing pain, one may gradually achieve unity of knowledge and action in that matter, but when the pain is forgotten, they might act according to their whims.