Why is paying for things painful?Why are we comfortable overpaying for something in the present just because we've overpaid for it in the past?Why is it easy to pay $4 for a soda on vacation, when we wouldn't spend more than $1 on that same soda at our local grocery store? We think of money as numbers, values, and amounts, but when it comes down to it, when we actually use our money, we engage our...