Rather than teaching mental skills, see it as re-organising the filing cabinet
Assume that players we initially see as having a 'deficit' actually have all the mental skills they need, just not a language to describe them yet.
Think of it another way. Imagine the player's memory like a disorganised filing cabinet, with nothing organised in the right place and nothing written on any of the labels. In the players filing cabinet is all the memories of using mental skills they will ever need, but not organised into any filing system, making them difficult to access.
We all have experiences of thinking things to ourselves (self-talk), imagining objects and outcomes (imagery), doing things to try and relax or psych ourselves up (arousal control), deciding on something that we want and thinking about how we might get it (goal-setting).
Players often overlook these experiences as examples of the valuable mental skills that they already have. Why? Because they haven't labelled them in their filing cabinet yet, and so can't access them easily.
In my practice I look to ask questions about these 'instances' when players have used mental skills, even if only to partial success. 'What would you call that skill? Tell me more about how you did it? What helped? What did it take do that? How could you use it again?'
So when coaching mental skills, particularly to young athletes, consider:
1. How you can help athletes quickly find the mental skills in their filing cabinet.
2. Whether your role is to fill the filing cabinet or just help re-organise it...