A. If your athlete is under about 13 or so, then it is advisable to do the training with them. This is a fantastic bonding and connection experience that also allows you to integrate it with your team's values. 5-12 minutes at a time keeps their attention.
B. For older or mature athletes, I made a special video talking to them directly that you can access here: Mental Toughness Trainer Talking to Young Athletes Directly. The key to getting athletes to do any type of mental game work is to point out the problems and issues they are having that are solved by having confidence. It's not a tough sell at all for kids to want confidence. Just ask them "How would you like to be a lot more confident?"
C. You have a 60 day, no-questions-asked money back guarantee if your kid never gets to the training.