All of the most positive and powerful thinking you can summon won't cause a trade to go your way if the market has something else in mind.
Having said that, the PDF is one of the best pieces I've read on the overall subject of discipline, and it sure speaks directly to many of the problems I've faced over the years.
How many of us have pissed away hard earned system profits by then "winging" it while watching charts when we should have been doing something - anything - else. Or how many trades have busted our P&L when we took a small system loss and felt we had to get it back, only to lose even more?
(Recommendation for any traders struggling with this. Everytime you wing it outside your rules, slap yourself in the face. It works for me.)
IMO, understanding your psychological makeup, and conforming it to the needs of the trading environment, is a very, very difficult thing to do. But a key to survival.