Health is the most precious gift, the best wealth that a person receives from nature. Systematically conducted hardening helps to preserve it, protect oneself from various diseases, increase the body's resistance to adverse environmental influences. Candidate of Medical Sciences A.P. Laptev tells about what hardening is, how to carry it out in everyday life. The brochure outlines the methods and methods of hardening with air, sun and water. Recommendations are given on the use of artificial ultraviolet sources.