This is the first step to become a fitness instructor: love this profession and be passionate about it. With the determination to do things, the rest is left to training to learn. To be an excellent personal trainer, you need to pass the certification and establish your personal brand (focus on the key points, personal brand is very important, it can distance you from other coaches).
In this process, you need a lot of time to train and study, and constantly shape your positive image. Although many coaches have a solid foundation and their own teaching methods, their coaching career has been spent in obscurity because they don't know how to manage their own personal brands.