…not the athlete you once were.
Many high school coaches were once high school athletes of the sport they are now coaching. Some of them were even college athletes of the sport they are now coaching. And occasionally you might find a high school coach who was a former professional athletes in the sport they are now coaching. If I could give one piece of advise to a new coach or a coach going to a new school or club, it would be to remember that the group of young athletes in front of you are not you.
Not only will they perform differently than you, they will likely be motivated differently than you. I am not suggesting that you set different standards of work ethic or preparation. But I am saying that you have to get to know your athletes and come up with plans on how to best motivate and inspire them, taking into account their exposure and experience of the game. It is okay to work towards a goal of getting your athletes to love your sport as much as you do, but recognize that only a handful of your athletes will reach that goal. It is a coaches job to bring a bunch of individuals together and build a team, working towards a common set of goals. Be honest in your assessment of your players and be sure you are coaching the athletes you have.