One of the books that I've been reading lately is "Vision of a Champion" by Anson Dorrance, the UNC women's soccer coach and winner of close to two dozen NCAA Championships. In the book, Dorrance talks about such things as working towards personal excellence, the competitive cauldron, and developing a winning mentality. He also devotes a chapter to parents and other supporters who, if not careful, can do more harm than good to their child's long term success. So far it's a great book that should be read by coaches, athletes, and parents.
Here's a short excerpt from Chapter 5: "The winning mentality is partly optimism, but mostly its a combination of focus, pride, competitive anger, relentlessness, hardness, fitness and courage - all the most descriptive words for competitive athletics. This type of mentality is not about skill or tactics. What it comes down to is intense desire. To get this winning edge you need to build an indomitable will. This means you must be relentless; you must never give up."
"What I love about this mentality is that it's not a talent; it's not part of a genetic code you're either born with or not. It's a choice, a decision you make to develop it. It's not an easy choice, but it is what is going to elevate you from the ordinary player. The question is: Can you make the choice to be indomitable?"