Retailers often offer incentives to encourage customers to buy more stuff. This can look like buy two get one free, buy one get one 50% off, flash sales, and free shipping thresholds.

Most of these mechanisms are designed to short circuit your brain. They work against clear thinking; they give you a limited time constraint to stop you from thinking, to discourage clear decision making. It works because it makes you feel like you’ve saved money, or you got a good deal.

While this practice happens internationally, I notice this particularly in Hong Kong, where outlet malls offer deals like buy four get 70% off everything. So you walk into a store with one shirt in mind, and you leave with four—but you spent more than you ordinarily would have.

Here’s how I started thinking about it: every dollar I save is a coupon on the next thing I buy. I was recently at a bookstore that offered brand new copies of magazines that were several months old, at a 70% discount (!), and I was on the fence—until ultimately I just decided I didn’t need it and it would be a discount towards whatever the next thing I bought was.

I also decided I would not buy things at discounts unless I had already put an item on my shopping list. I would rather pay the premium of buying something at full price, and having the clarity of mind to think about it, than to go through the fever pitch of buying, buyer’s remorse, and navigating a return.

“Show me the incentive and I’ll show you the outcome,” Charlie Munger says. This reframe is an incentive to not buy more than you need—and instead, to mentally (or literally!) create a coupon towards the next thing that you buy.