There are some great parallels between athletes who excel and true sales professionals who excel. After spending four years following my son, Leon's NCAA Division I hockey career, and now two years as a professional (he is in the L.A. Kings system) I've gained a lot of knowledge from and respect for athletes when it comes to how they train, think, and condition themselves.
For example, the saying, "The more one sweats in practice, the less one bleeds in battle" - works for both professions.
Another commonality is the "Little Voice Management System" first described to me by Blair Singer. Successful sales professionals, like successful athletes have developed an internal monitoring system so that there is little or no negative self talk - unlike the rest of the world. If you don't have a good LVMS, consider creating one. It works!