The decision

Everything so far comes down to one decision. It isn't to stop shopping, and it isn't to spend less, though you probably will. It's this. You stop buying things on the day you first want them.

That's the whole rule. A want that arrives tonight can't be paid for tonight. It goes on a list with a date, and it can be bought on a later day if it's still wanted. You lose nothing you'd have been glad of. A real want comes through a wait with no trouble, and for a want that was made by a mood the wait is usually the end of it.

Here's how I'd set it up. Some of it happens in the moment, and the rest is arranged in advance.

Notice what you're shopping for. When you find yourself browsing, say to yourself "I'm after a lift." It isn't an accusation. It moves your attention from the bag to the evening. Then ask what happened today.

Ask the question. Did I want this yesterday? If yes, and you'd planned to buy it, go ahead with a clear mind. If no, carry on to the next step.

Put it on the waiting list. Keep one list, on paper or on your phone. Write the thing, the price and today's date. Enjoy the choosing as much as you like, because that part is free. Then close the tab without paying.

Give the evening what it needed. Look back at chapter 14 and pick one. Put a date in the diary, ring someone, finish one small job or go to bed.

Read the list on a good morning. Once a week, when you're rested and in an ordinary mood, read down it. For each item more than a few days old, ask whether you still want it, and what it'll be in its third month. I suggest waiting a week for small things and a month for anything that would make you wince. Those periods are my suggestion and nothing more scientific. Cross off whatever has gone cold. You'll be surprised how much has.

Buy what survives, and enjoy it. If something is still wanted after its wait, buy it without guilt. It's a planned purchase now. Watch for it in the sales if you like.

Then there are the arrangements, which take one evening and put back the pauses that chapter 7 described. Delete your saved cards from the shops you use most, so that paying means getting up to find your wallet. Unsubscribe from marketing emails, all of them, in one sitting. Take shopping apps off your phone and turn off their notifications. Decide that pay-later schemes are for planned purchases only, if you use them at all. Each of these gives you back a few seconds, and you don't need more than that to ask the question.

Plans of the form "when this happens, then I'll do that" have a good record in research on habits, because they attach the new response to the moment that needs it. You could make three. "When I notice I'm browsing in the evening, I'll ask what happened today." "When I'm about to pay for something I didn't want yesterday, I'll put it on the list and close the tab." "When I see a countdown timer, I'll leave the page."

As for what to expect, the urge to browse will keep turning up on flat evenings, probably for good, because flat evenings keep turning up. An urge is only a feeling, and you can have it without doing anything about it. With practice I'd expect the list to take the heat out of most of them within minutes. I'd expect fewer parcels and more money at the end of the month. I'd also expect the things you do buy to please you more. That's what I expect and I can't promise it, because the method hasn't been tested as a package. You can test it on yourself, though, and a month is long enough to see.