Each individual has different abilities, different individuals have different physical conditions, each individual has different mental and physical strength, beyond the individual’s ability and tolerance, long-term burdened forward, our body may have physical problems, and then psychological problems. Human tissues, organs and systems each have their own functions, and if they work beyond their functional limits for a long period of time, individuals may develop functional reactions, and in serious cases, develop from functional reactions to functional diseases. If timely and effective adjustment is made, the person may recover well; if the adjustment is not good, the person may only recover to a certain level. People are subject to various stimuli, including stimulation of internal and external environmental factors in the operation of life, as well as mental and physical activities. All these stimuli will be handled by the nervous system coordinating the whole body system, and finally the stimuli will all act on the nervous system, causing nervous tension, that is, the nervous system is in a working state. This state, if it can return to normal, belongs to the normal physiological function; if not, but the tension level is gradually raised, it may exceed the nervous system’s working capacity, and a functional reaction may occur. The amount of stimulation that the nervous system can withstand in a lifetime is not unlimited. If the amount of stimulation endured within a certain period of time exceeds the normal physiological function, functional reactions may occur, and in serious cases, functional diseases may occur, even affecting the normal physiological process. The growth process is significantly less likely to result in a functional response because of the dynamics of growth. Stimulation causes neurological tension, which is gradually elevated as the amount of stimulation becomes greater, the degree of stimulation becomes heavier, and the duration of stimulation becomes longer. It is not easy to notice within the normal physiological function, and after a certain level of functional response appears, we notice it and begin to think about it and seek the cause. And if there is a serious functional reaction, we feel shocked and even panic. Because it is a feeling that never existed before, repeated tests are inconclusive, either everything is normal or the current physical condition and disease cannot be explained. And repeated thoughts and tests continue to increase the nervous tension and aggravate the functional reaction. This can make us feel confused. Thinking is a mental activity, and mental activity is mental work that is done with the brain-based nervous system. Normal mental activity is accomplished by normal physiological functions and is accompanied by a certain amount of energy expenditure. Excessive mental activity, accompanied by a large amount of energy consumption, is part of the stimulus that may trigger functional reactions and sometimes becomes the main cause of triggering functional reactions. The diseases that humans face can be divided into two categories. One category is organic diseases, which are diseases of an organ or a tissue system of the organism caused by multiple causes that result in systemic damage to the organ or tissue. The other category is functional diseases. In contrast to organic diseases, they are mainly due to the dysfunction of the cerebral cortex, resulting in a series of clinical symptoms caused by autonomic dysfunction. Due to the wide distribution of autonomic nerves in the human body, the clinical symptoms produced when its function is dysfunctional are often diverse and similar to the organic symptoms, which are easily misdiagnosed as organic diseases, resulting in poor treatment results. Generally speaking, it is a clinical symptom caused by the dysfunction of the nervous system that innervates the organs, without any change in tissue structure, and the condition is mild and usually does not have serious consequences, such as neurosis, which can have symptoms such as headache, dizziness, weakness and insomnia, but no substantial damage to brain cells. Therefore, beyond the individual, beyond the human body tissues, organs, systems, beyond the function of the nervous system and the amount of load, especially beyond the function of the nervous system and the amount of load of the state, if not adjusted in time to restore, are by the possibility of functional reactions, or even functional disease. If this happens, we should not only do a psychological assessment, but also a functional assessment. So, what should we do? It should be adjusted according to the physiological rules, which generally means, regulating the mind, strengthening exercise, living normally, eating well, avoiding overwork, etc., so as to keep the mind and body healthy.