If the rule only applies when it’s convenient for you, it’s not a rule. It’s a mood.

A standard that bends whenever it costs something is not a standard, it is a preference wearing better clothes. The whole value of a rule is that it decides for you in advance, especially on days when your judgment is compromised by tiredness or self-interest. Applied selectively, it stops guiding anything and becomes a way of explaining what you were going to do anyway.

Take one rule you claim to hold and find the last time honoring it cost you something. If you cannot find one, either keep it the next time it is inconvenient or stop calling it a rule.