Everyone here is describing the same trade
Rohn calls it two kinds of pain, Epictetus calls it mastery, Maxwell calls it the difference between starting and continuing — but the structure underneath is identical. You pay now in small, boring instalments, or you pay later in one large one. The reason the advice keeps being reissued in new words is not that it is complicated. It is that nobody enjoys it, and each generation hopes the previous one was exaggerating.
Nietzsche to a Navy SEAL, and the same sentence
The oldest line here is Nietzsche's from 1883 and the newest is Jocko Willink's from 2018: he who cannot obey himself will be commanded, and discipline equals freedom. They are the same argument, a hundred and thirty-five years apart, made by a philologist with migraines and by a commander of a SEAL task unit. Seven of the twenty-one lines here are sourced exactly, and the two that bracket the room are both among them.
Did Aristotle say “we are what we repeatedly do”?
No. The line is Will Durant’s, from The Story of Philosophy in 1926, where he is paraphrasing Aristotle’s argument about habit. The idea is genuinely Aristotle’s; the memorable sentence is Durant’s.
What is the difference between motivation and discipline?
Motivation is a feeling and it fluctuates; discipline is a decision made in advance so that the feeling stops being the deciding vote. Maxwell’s line puts it most simply: motivation starts things, discipline continues them.
What is the full version of “We are what we repeatedly do. Excellence, then, is not an act, but a habit…”?
Almost always credited to Aristotle. It is Durant, summarising him — the phrasing is the historian’s, not the philosopher’s. The collection cites it to The Story of Philosophy, 1926.