"No pain, no gain" is an impaired mental state diametrically opposite to the manner the best of the best train and compete. Inflicting self harm: stressing your body to the point of pain, injury, and illness is not physically, mentally, nor emotionally healthy. Training ideologies based on "PR or ER" are cancerous & result in athlete's blowing up, melting down, or burning out.
Characteristics of a Champion  – Josh Waitzkin
Joshua Waitzkin (born December 4, 1976) is an American chess player, martial arts competitor, and author. As a child, he was recognized as a prodigy, and won the U.S. Junior Chess championship in 1993 and 1994. He is the only person to have won the National Primary, Elementary, Junior High School, High School, U.S. Cadet, and U.S. Junior Closed chess championships in his career. The movie Searching for Bobby Fischer is based on his early life.