What do you intend by the analogy? That the instantaneous effort it takes to sustain a course is less than it takes to commit to and begin it?

I agree that where possible it makes sense to order your life so that what you should do is in fact easy and even pleasurable. I'm not worried that, if I become too comfortable, my willpower or desire for novelty will atrophy, but if I were, I would set up a metaphorical alarm clock to wake me from my too-comfortable routine.