We should avoid ruminating on what went wrong—“If only I hadn’t done that.” That’s called subtractive thinking. What works is additive thinking. Say you’re playing basketball: Rather than saying to yourself, “Oh, if only I’d made that shot,” think, “I have another strategy I didn’t use. Next time I’ll drive to the hole and then I can shoot or dish it.” If you think about things that didn’t happen that you’d like to do next time, you can prime your brain for better performance after a failure.
Po Bronson quoted in Wired magazine