"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.
Physical Training – TED & 99u talks
Lissa Rankin, MD: Is Medicine Killing You?
Lissa Rankin, MD: Shocking Truth About Your Health