How well are you prepared mentally for the situations that you will face during the course of a match?
It is difficult training your mind on your own?
You can start from the next high-level match that you will watch on TV and concentrate to the player of a team that plays in your position.
See how he reacts to various stimuli and how he copes to the needs of the game. Simultaneously retract your own moves and decisions in similar cases in the past.
When you finish the game you have to feel tired mentally from the identification with the player watching.
Besides you train your mind in this way ...