The 72-Hour Rule
Kill most impulse spending without ever writing a budget.
Impulse buying is not a willpower problem. It is a timing problem. You want the thing and you can buy it in the same second, and nothing sits in between.
Wanting something is a spike, and spikes fade — usually faster than you expect. Wait a few days and what is left is closer to a real preference. Three days is a working number, not a measured one; the point is that any delay beats none. The rule never asks you to say no. It asks you to say later, and a tired person can still say later.
Pick a number
Choose an amount that stings a little relative to your own budget, not a figure from someone else's. Roughly half a day's take-home pay is a reasonable start. Anything above it waits.
Write it down instead of buying
Do not close the tab and hope you remember. Put the item on one list called Waiting, with the date and the price. The list is the system.
Come back on day three
Look at anything older than seventy-two hours. Buy what still makes sense. Delete the rest.
Add up the deleted ones
Once a month, total what you did not buy. That number is what the rule earned you. Seeing it is what keeps the habit alive.
Go deeper
What the paid version adds to this one.
A calculator that sets your number from your real income and fixed costs
The version for households, so one person wanting something does not quietly become a joint purchase
The four kinds of purchase where the rule backfires, and what to do instead
The monthly review, filmed start to finish on a real list