As important as your athletic training is your Mental Toughness. There’s considerable debate and discussion surrounding this topic, but the term is one that I can really connect with.
A study from Penn State University resulted in the following definition: Mental toughness is having the natural or developed psychological edge that enables you to: Generally cope better than your opponents with the many demands (e.g., competition, training, lifestyle) that are placed on you as a performer. Specifically, to be more consistent and better than your opponents in remaining determined, focused, confident, resilient, and in control under pressure.
Here are a few links to other perspectives on Mental Toughness:
The NAVY Way: http://www.mentalgamecoach.com/articles/MentalToughnessTheNavyWay.html
Penn State: http://www.mascsa.psu.edu/dave/Mental-Toughness.pdf