Everyone wants to be healthy, but how can you know whether you’re healthy enough? We can deconstruct, health has three levels: the first level, called function and demand. The first level is called the adaptation of function and demand. This level is easy to understand, that is, your body can adapt to your needs. How to judge whether it is adapted or not? This is not a question that can be answered by a physical examination, but by you, the person who has firsthand experience. It sounds a bit mysterious, but let me give you some examples to make it easier to understand. For example, the smallest thing, your teeth are good, can you eat comfortably and feel satisfied? With your neck pain, can you finish today’s presentation? To a slightly larger thing, you worked for 8 hours today, from the morning alertness to the afternoon drowsy, but your thinking response, on the whole, can still meet the needs of the work. Another example, is you do housework on weekends, go to the park with your children, managing a hectic schedule, you can also follow. All of these are called matching functions to need. This concept of health, from beginning to end, did not mention that all the laboratory indicators must be normal. If your medical reports are normal, but you just feel tired and can't cope with the day's work, that's also unhealthy. To judge whether your body is functioning adequately, your perception is the first basis. Of course, it is not enough to be physically fit. In the past, we did not care about the psychological aspect of our health, no matter whether it was medical checkups or health management. Nowadays, the second level of health is the pursuit of physical and mental harmony, that is, the WHO’s definition of health proposed by the WHO regarding health. How to judge this level of health? It depends on your perception as well as some technological means. For example, if you work late until one o'clock and have an important meeting tomorrow, and you want to go to bed and can't sleep - is your insomnia a problem, you need to rely on a standardized assessment tool. Another example is when you know you shouldn't be angry with your child, but you can't help it when you are tutoring him or her, and your blood pressure goes up. You need a blood pressure monitor to determine how high your blood pressure is and whether you should take care of it. To determine whether your body and mind are in harmony, you will need to use some basic self-assessment scales, as well as daily monitoring gadgets, such as blood pressure monitors, wearables (e.g., heart rate monitors, sleep trackers), and so on. The results of your monitoring, your feelings, and the results of your medical checkups all add up to a complete picture of physical and mental harmony. In addition to adaptation and harmony, there is a third dimension to health, which I call potential, that is, the energy that your body and mind are capable of mobilizing in response to adversity and stress. When the storm comes and the pressure is on, your body and mind have to reserve enough energy to fulfill your wishes. It may be that you are on a plateau, running a marathon, experiencing a cold, facing the COVID-19 pandemic, or your job requires you to fight for some time. During these tough phases, your body and mind need to have enough reserves to carry you through. It's not that easy to make good health judgments at this level. For example, the core of the body's reserves is your cardiopulmonary function, which can be obtained through professional medical tests, but for other organs, such as the digestive tract, and kidney function, it is difficult to rely on medical means to routinely measure, as well as your psychological resilience, it is also difficult to quantitatively measure. At this point, it comes back to your perception, you need to carefully observe your body's functions, once you feel that there is a mismatch or insufficiency, it is the moment when your reserves are about to be depleted and your health is out of balance, so you need to be extra careful.