If you have trouble controlling the amount and frequency of your credit card purchases, try putting your credit card in a glass of water and putting it in the freezer. This makes it so every time you want to use your credit card, you’ll have to wait for the credit card to melt. By the time the ice has thawed, your desire to impulsively purchase may have evaporated as well. I read about this in Predictably Irrational; Dan Ariely called it, “The Ice Glass Method.” Apparently, it doesn’t ruin the credit card, although it will if you try to microwave-defrost it. This method is probably only good for people who do their shopping sprees in-person. Online shopaholics would just look through the ice.
Sometimes creating self-imposed barriers can be just what we need to curb bad habits. The same person inside us who has the willpower to put the credit card in the freezer is different from the person inside us who doesn’t have the willpower to resist picking up the plastic and hitting the shops.