" Studies on the phenomenon indicate that a person with a high tolerance for pain is likely to also have above-average capacity to cope with the stress of a job layoff or a cancer diagnosis, and this same person is more likely as well to have experienced a moderate amount of psychological trauma in his or her past. It would appear that a certain amount of misfortune is needed to toughen the mind against suffering and hardship, but excessive trauma leaves scar tissue. "

― Matt Fitzgerald , How Bad Do You Want It?: Mastering the Psychology of Mind Over Muscle