If there’s an article-length version of Atomic Habits, published years prior to the best-selling book, this might be it.
Motivation is like manually winding up a crank to deliver a burst of force. At best, it stores and converts energy to a particular purpose. There are situations where it is the correct attitude, one-offs where getting psyched and spring-loading a metric fuckton of mental energy upfront is the best course of action. Olympic races and prison breaks come to mind. But it is a horrible basis for regular day-to-day functioning, and anything like consistent long-term results.
By contrast, discipline is like an engine that, once kickstarted, actually supplies energy to the system.
Productivity has no requisite mental states. For consistent, long-term results, discipline trumps motivation, runs circles around it, bangs its mom and eats its lunch.
In summary, motivation is trying to feel like doing stuff. Discipline is doing it even if you don’t feel like it.