The Pain of Discipline
There are several working definitions of discipline but one that I especially like is "doing what needs to be when it needs to be done, whether you want to do it or not." If you believe this definition then you must agree that discipline is not necessarily something you have but rather something you choose to use.
Being disciplined is a great personal quality to have, but for most players it is extremely difficult to remain disciplined over time. It's not easy to do individual skill work out day after day after day. It's not easy to get in the weight room day after day after day when you are already tired after practice.
It's not easy to do go to practice and grind out the same drills day after day after day. There is almost always some pain associated with being disciplined. There is the obvious (and often constant) physical pain. There is the mental pain that comes from constantly trying to convince yourself that you are doing the right thing. Then there is the emotional pain that comes from working as hard as or harder than everyone else and not getting the same rewards or recognition.
I think one of the things Coach Stevens was alluding to in his interview is that the Butler players are willing to put up and work through all the pain that being disciplined requires in order to commit fully to their team's goals and culture. And as long as the players are disciplined and committed to the process of development and improvement, then Coach Stevens can live with the results if they happen to lose.
The Pain of Regret
On the other hand is the pain of regret. Basically, if you don't exercise the necessary discipline in order to be successful now, you will eventually look back and regret your decision. And what's worse is that regret will undoubtedly never go away. This is the ultimate pain of regret.
I have talked to dozens of people over the years who have confessed that they "could've" been great players, been great teammates, had great careers, and reached their fullest potential if only they had used a little more self discipline. Imagine yourself telling your own kids or even your own players if you happen to coach some day, "I could've been a great player when I was your age but it was just too hard to eat right, get enough sleep, and to work on my game." What do you think their reaction is going to be?
As a player you have to make decisions and choices every day. What are you going to choose - the pain of discipline or the pain of regret?