The article describes the possibility of using the data on the health status and lifestyle self-assessment obtained during the questionnaire survey of high school students in the teacher's preventive activities aimed at preserving and improving the schoolchildren's health. The main indicators that according to the respondents determine their quality of life have been revealed, and health status is ranked only third. It has been found that 40% of students consider their health to be “good”, while 53% currently do not worry about their health at all. Certain characteristics of physical activity, nutrition, sleep schedule, prevalence of bad habits in students attending schools of various types are provided. Despite high subjective assessment of physical activity, only 8% of schoolchildren do morning excercises every day, most of students do not attend sports sections. More than 40% of students sleep less than seven hours, which has a negative effect on the adolescents' health. Evidence has been obtained that 19% of schoolchildren have tried vaping and 13% vape regularly, which is definitely worrisome.