Almost every expensive mistake has the same shape: a decision made in a state of momentum, where stopping felt like losing something. Retailers understand this precisely, which is why countdown timers, low-stock warnings and limited-time bundles exist. A deliberate delay is the cheapest defence available, and it costs nothing but patience.
Pick a threshold that matters in your budget — it might be a hundred dollars, it might be a thousand — and commit to waiting two days on anything above it. Not researching, not justifying: waiting. The purchase goes in a list with the price and the date, and you come back to it when the mood that produced it has passed.
Most items fail quietly. You read the line two days later and feel nothing, which is useful information you could not have had in the moment. The ones that survive tend to be the purchases you had already been thinking about, which is exactly the category where spending is usually fine.
The rule also fixes the opposite problem. People who are chronically reluctant to spend often postpone genuinely useful purchases indefinitely, and a written list with dates makes that visible too. After forty-eight hours the question stops being “do I want this” and becomes “is this still on the list”, which is a much easier question to answer honestly.
