Question 122: Mental aspects

I was searching for an insight on the mental aspects of my game, I am a semi pro squash player and have been playing for most of my life, I have read your article on physical or mental regarding Taekwondo, and felt like I could definitely relate to the fighter who is physically better with better technique but loosing to inferior opponents. I did love the article and find it very interesting but the real question I wish to ask is how do you go about increasing your mental abilities? I wish to be able to beat all the inferior opponents but I do not know how to go about increasing my concentration. A push in the right direction would send me over the moon.