Discipline is remembering what you wanted before your mood started negotiating.

Your mood is an excellent negotiator. It arrives with reasons that sound like insight, points out how tired you are, and proposes a compromise that happens to match exactly what it wanted anyway. Discipline is not force applied against that. It is memory, holding on to the thing you decided when you were clear and no one was tired.

Write your intention down while you still mean it, in words specific enough to survive being reinterpreted later. Then treat the evening version of yourself as a party to a decision rather than the one making it. The note is not a rule; it is a message from someone who knew what you wanted.