Discipline is self-respect expressed through repetition.

Doing what you said you would do is a form of treating yourself as someone whose word counts. Every kept commitment quietly confirms that your intentions are not decorative, and every abandoned one suggests the opposite, whatever you tell yourself afterwards. This is why discipline feels good in a way that has nothing to do with the task. It is the ongoing act of taking yourself seriously.

When a routine feels pointless, ask what keeping it says about how you regard yourself. Then keep it for that reason instead of for the outcome. On the days when the results are invisible, that is usually the reason that holds.