The most important duty of a fitness instructor is to help customers become healthy. Customers who come to exercise need scientific fitness guidance to get healthy. Therefore, a fitness instructor should have professional knowledge of human anatomy, physiology, medicine, nutrition and sports skills, in addition, he should also know psychology. Because coaches should be good at communicating with customers, accurately understand customer needs and provide help.

Being well informed is the basic quality of a fitness instructor. For example, in order to achieve the best effect of fitness exercise, the coach should also be a "personal doctor", who should have certain health knowledge and understand the diet, work nature, sleep quality and so on of the members.