This is probably pretty obvious but I think it often gets forgotten, you should be your biggest fan!
All too often, especially with young players they not only have to beat their opponent but they have to conquer themselves as well. If you watch a team sport I don’t think they play any better if the crowd is against them. In table tennis, most of the time my players are not being supported by a crowd of spectators, if they are lucky they will have a coach and maybe their parent in their corner supporting their efforts but most of the time it is just them on their own.
So why when they lose a point are they the first to criticise their efforts? And often or not they are the last to appreciate it when they play a good shot. Mistakes are made that is the nature of the game. I think it very important that players move on to the next point and don’t dwell on the past. The energy they use to criticise themselves is wasted and I feel this negative energy affects their play and their psychological state of mind.
A positive state of mind is a crucial element in play, a quick analysis of what went wrong and a tactical adjustment is what is more likely to be required and in the short space of time between points letting your negative emotions take control does not lead to good decision making.
Secondly letting your opponent see your emotional weakness leads to an increase in their confidence and confidence often leads to better play. These emotion patterns are often developed early on and difficult to change when established. Encouraging an emphasis on keeping a positive state of mind needs to be introduced as early as possible.
I encourage my players to smile at their opponent after a net or an edge giving them a conditioned response that helps them focus on what needs to be done. Some players respond to having a music theme in their head using it as a refocusing technique, whatever method you choose keep positive and leave your negative criticism for the training hall.