One of the problems with being "rational" in your own estimation is that you are probably only being rational about one dimension of a surprisingly complex situation
Spend less time focusing on "discipline," and more time in things that genuinely pull you forward...
The person who requires internal force, will always get lapped by someone with genuine drive toward that thing.
Obsession beats discipline all day long.
When you feel like things are hard, your instinct might be to ask “why are things this hard?” Or to curse your luck — but a better question would be “why should things be easy?” Like why are you owed that when the natural state of things is difficulty.