I believe that a smart person can understand some principles. For example, sunk costs should not be included in decision-making considerations, so wrong actions should be stopped in time; appropriate exercise and regular routines are beneficial for physical and mental health; weight loss requires controlling the mouth and moving the legs, and so on. However, to practice these principles requires more wisdom. The gap between being smart and being wise is the gap between knowing and doing. After understanding some principles, how to achieve the unity of knowledge and action in practice is very difficult. This requires us to overcome human tendencies to seek profit and avoid harm, to seek ease and avoid difficulty, and to find ways to make the things that should be done easier to do and the things we want to do more reasonable.