“The problem isn’t so much whether regret is an unproductive emotion. It’s that regret occurs after the fact, instead of before. As Nietzsche points out, regret can do nothing to change what has already happened. We just wallow in remorse about something over which we no longer have any control. But if regret occurred before a decision instead of after, the experience of regret might get us to change a choice likely to result in a bad outcome. Then we could embrace Thoreau’s view and harness the power of regret because it would serve a valuable purpose. It would be helpful, then, if we could get regret to do some time traveling of its own, moving before our decisions instead of after them. That way, regret might be able to keep us from making a bad bet. In addition, it wouldn’t, as Nietzsche implied, rear its head later by causing us to make a remorse-fueled second mistake.”