“Discipline” is a scary word for some people. Given the experience some of us had with public education, and in the workplace, this is not surprising. In those cases, it’s likely that “discipline” meant something a lot like “punishment” but that’s not what we’re talking about here.
In this case, it’s about being able to exercise a sufficient amount of control to produce socially appropriate and desirable behaviors. One of the immediately apparent implications is that discipline is a given -– the only choice we have is whether it is self-imposed or externally imposed.