Mental Toughness is a cop out. I believe mental discipline trumps so called mental toughness all the time. All the champions I have been around had incredible mental discipline. Making someone puke in a workout or running someone until they drop does not build mental toughness. Find out who will do the workout when no one is there to make them do it. Find out who shows up and brings their "A" game every day no matter what the conditions and circumstances. Those are the people who have mental discipline; those are the people I want on my team.