While in this context the idea of a "myth of discipline" seems to fit, I would disagree with it within a larger context. Yes, desire is a much stronger motivator, and building the desire for what you really want works in fitness. Discipline is not a myth, and being able to stay a course that is difficult, tedious or fraught with setbacks requires more than love, it requires discipline. habit can help, building the habits that support fitness and health can ease the difficulties, we are comfortable in our routines and something repeated often is easier to do than something we do rarely. There are many ways to enhance motivation: Positive feedback, progress, positive social environment that supports the desired habits and end goal. There are times when sheer bloody mindedness is all that is left, and not giving up is more important than succeeding. But that is not discipline either. Discipline is knowing what the right thing is and doing it in spite of contrary motivations, distractions, difficulties or social pressures.