Draw one clear, binary line

Replace "less" or "moderate" with a rule that is unambiguously on or off.

Why it works

A vague rule ("eat healthier") requires a fresh judgment every time, and each judgment is a chance for willpower to lose. A bright line is binary — you either crossed it or you did not — so there is no degree to argue about. The clarity itself is the lever: it converts a continuous, negotiable spectrum into a single yes/no that the brain cannot bargain with.

How to do it

1. Restate your goal as a rule with zero ambiguity ("no screens after 10pm", not "less screen time").
2. Make sure any observer could tell whether you kept it — if it needs interpretation, it is not bright.
3. Pick a line you can actually hold; an impossible bright line just becomes a daily failure.

Evidence

Grounded in research on decision fatigue and on the reliability of simple rules over case-by-case judgment. The "bright-line" term is borrowed from law; its use for personal habits is a heuristic. (mechanistic)

Clear rules reduce in-the-moment failure but say nothing about whether the rule is wise; a bright line around the wrong target is still wrong.

Common mistake

Writing a rule that still contains a judgment call ("only a reasonable amount"), which quietly reopens the negotiation the bright line was supposed to close.