Oxygen is the basis of life on Earth. If organs and tissues are not sufficiently supplied with oxygen, hypoxia occurs and diseases develop. There is enough oxygen in the environment, but very often the body is not able to absorb it in the required volume. The body’s ability to extract oxygen from the air and deliver it to cells and tissues is called aerobic, It is they who determine the “amount” of a person’s health and the degree of his endurance. Aerobic capacity can be developed. But this should not be done in the gym, but on a treadmill! Strength training on exercise machines is absolutely useless and even harmful. In order to increase the physical capacity of the heart and lungs, long-term cyclic training with a uniform and feasible load on these organs is necessary. Healthy walking is the most accessible and safe form of aerobics, which allows you to increase the reserves of the circulatory and respiratory systems almost from scratch at any age without the risk of cardio overload.