John W. Mahoney, Daniel F. Gucciardi, Clifford Mallett, and Nikos Ntoumanis The Big Idea It would be difficult to find an adult athlete or coach who doesn’t have a favourite quote on the need for mental toughness in competitive sports. Who hasn’t heard the general adage that success in sports is 10% physical and 90% mental? Or who among us hasn’t read the mighty locker room posters from the past: from Babe Ruth, “It’s hard to beat a person who never gives up;” from Bobby…