Think back on the past week. What’s your biggest regret? Did you tell a joke that fell completely flat, or walk into the wrong bathroom by mistake? Now think back longer. We’re guessing that if you’re recollecting your regrets from the more distant past, most of them aren’t embarrassing things you did or said. Chances are, most of them are things you never did at all.

Here’s a scenario adapted from Daniel Gilbert’s book “Stumbling Into Happiness”: Imagine you win a million dollars. You get the phone call, freak out, tell all your friends, invest all the money in the next big company — and then promptly lose everything. Okay, rewind. This time, you just won a million dollars, but you missed the phone call and they give the money to somebody else instead. In both cases, you made a mistake. But which one will you regret the most? Although…