How should you play a game?

I had played a TT match in our office and lost. I thought I will share with my son Aditya the lessons that I learned from the loss.
"Before starting the game itself, I thought that I will lose the game. Thoughts are very powerful and they guide our actions. Since I had already decided that I was going to lose, I played to lose the game" I told him, very pleased with myself having imparted this wisdom.
"Do you know why you lost?" he asked me.
"Because I had decided that I will lose?" I was little bit surprised at his question.
"You lost because you were very focusing on thinking about losing while your opponent was focusing on playing the game."
Now I am not sure who delivered the wisdom.