When I first started coaching Mark, I noticed that it was very difficult for him to hold on to the agreed strategy. Now I am not a strong chess player so I focussed on the mental aspects.
The most obvious problem was fear. When the child panics he forgets. Too much fear shuts down the brain. Many times I asked him after, do you remember what we agreed? And he says, sorry, I forgot.
The next insight is not so obvious. Thinking is a bit like juggling a ball. First the juggler tries 2 balls and then more and more. What does this have to do with chess?
Well, first the child learns the technicalities on the board, he studies his opening, his tactics, strategy, end game etc. He becomes more proficient over time and with correct guidance. When he plays in a timed tournament he has to factor in time. He needs to remember his predetermined strategy etc etc. And in the beginning he always drops a ball. Eventually he remembers more and more, is able to hold more and more variables. He cannot do it all at once. He needs to be told that so he does not get discouraged.
Hey, I dont know many adults who can do all that. And to handle all that they need to manage their fears.
I want to leave a tickler here. If someone comes at you with a knife in real life, the fear mechanism can save you. From what is called the limbic route response, the fight or flight response. Now lets look at chess. Where does the fear come from? Is your opponent likely to stand up and punch you in the face? The ceiling fall down and crush the chess set? In my work, I call that imagined fears. See here.