As a group fitness instructor, your responsibilities are to lead a group exercise class at a gym, private studio, or another public space. Your duties are to teach your clients or the gym members who participate in your classes skills like good posture, proper technique for different activities, such as weightlifting, cycling, or swimming, and how to coordinate their exercise activities with other aspects of their lives. Some group fitness instructors work freelance and have gigs at many locations, while others are full-time employees of a gym or club.