“Health” is a blessing that we often apply, but different people have different ideas about what health means. According to the definition of the World Health Organization (WHO), health means not only the absence of physical illness, but also mental health, good social adjustment and morality. Our modern medical care can basically ensure that the average person is free from serious illness. However, due to the rapid social changes, changes in the working and living environment, and the expansion of interpersonal interactions, everyone is increasingly affected in the spiritual, mental and psychological aspects, and the problem of mental health is becoming more and more prominent. Sometimes, what appears to be just physical discomfort on the surface may have a potential cause in the psychological aspect. Self-evaluation plays an extremely important role in mental health. People with high self-esteem are usually stable, optimistic and cheerful, while on the contrary, they are sensitive, suspicious and depressed. Self-evaluation is not a thought that comes out of nowhere in a person’s brain, but is created in the process of long-term interaction with the outside world. Specifically, in the process of interacting with people around you, you judge your own value through other people’s attitudes toward you, and then form a position of your own value within yourself. For example, praise from a teacher makes one feel great, while criticism makes one feel bad. Usually, a person is still in the process of brain growth and psychological maturity until the age of thirty, so if the environment changes drastically and various psychological needs arise, it will lead to unstable self-evaluation and psychological fluctuations. After the age of thirty, the brain is mature, and the external evaluation of oneself has been gradually identified by oneself, so that a more solid pattern of self-evaluation will be formed, and will not change easily. “Thirty” is just a general turning point in a person’s maturity, the so-called “thirty and standing” is derived from this, but in fact, individual differences are relatively large, some people may be young and old, while some people may be old and cynical, and so on. Self-evaluation is a function of the brain, and the brain has “plasticity”, which means it can be changed. Although there is a saying that “the mountains are easy to change, but the nature is difficult to change”, it is not quite true. The way to change self-evaluation is not in oneself, but in the interaction between oneself and the outside world. For example, when the competition, usually behind others, despite their own desperate efforts to catch up, but still lost, not only by others to laugh, they may also feel that they are not that piece of material, self-evaluation is very low. But one day I suddenly wanted to change this situation, so in addition to training hard every day, but also secretly pay attention to other people’s training methods, trying to change their own training methods. So when the time came to compete again, the performance finally improved, and then the self-evaluation would rise dramatically. So, self-evaluation is completely changeable, its birth, from their own interaction with the outside world, and its change, must be through their own interaction with the outside world to achieve. Self-evaluation must be objective. Objective evaluation will produce positive results, but non-objective and distorted evaluation will lead to negative effects. For example, an exaggerated self-evaluation leads to the feeling that one is strong and everyone else sucks, or that others must respect one’s ideas while one need not respect others, etc. Negative self-evaluation, on the other hand, will feel that others always look down on them, that they are worthless, that they really should not be in this world, and so on. If these two kinds of distorted self-evaluation go to the extreme, it can produce paranoid personality disorder or even mental illness. What is an objective self-evaluation? The first thing is to learn to accept ourselves, to affirm ourselves, “no one is perfect”, no one is perfect, but no one is bad. We are all growing and learning in the process of doing better and better. Others do well to acknowledge, but also to believe that they can also do well. Time is the most fair judge, as long as the work is deep, iron pestle will be able to grind a needle. The second thing is to master the correct evaluation method. A person’s evaluation of their own can not be counted, their own evaluation of their own may not be objective (“do not know the true face of the mountain”), only after interaction with the majority of people will produce a more objective evaluation and psychological positioning. Third, is to learn more useful experience and knowledge of others, more thinking about how to specifically achieve self-worth, work to be practical, hands-on and not afraid of failure, more like-minded friends, more communication with others, and so on, of course, also to physical exercise, a good body will also have a good brain. In this process, they will gradually have a strong nerves, open vision, if the valley of the mind and friendly emotions, at the same time, self-evaluation will tend to be objective and true. Therefore, health is not only to ensure that the body does not get sick, but also to ensure mental stability and strength. In this way, no matter what difficulties and setbacks you encounter in life or at work, you will have strong enough physical and psychological resources to overcome the difficulties and meet the dawn of victory. In this way, it can be called “healthy” in the true sense of the word.