Update:Initially the inspiration for this post came from Loehr's book, The New Toughness Training for Sports. However, after falling on The Gold Mine Effect by Rasmus Ankersen, I've discovered a tremendous amount of research confirming and enforcing the power of mental toughness and positive thinking in achieving athletic excellence.Why do we stop when exercising? Traditionally (prior to the early 2000s), we believed that a decrease in performance is the result of physical fatigue - pointing to the the fact that less oxygen reaches the muscles, that lactic acid builds up and that our legs tire. The basis of this belief...