The real sting of regret, Twain suggests, isn't failure—it's the unlived possibility. We're equipped to rationalize our mistakes, to learn from them, even to wear them as badges of experience, but inaction leaves us with only the ghost of what might have been, and ghosts are harder to befriend. A person who took a job they hated will at least know themselves better for having tried; the person who never applied for the position sits forever in the country of "what if," where the imagination grows weeds instead of roots. That's why the quieter decision—the email not sent, the conversation not started—tends to haunt us longer than any spectacular stumble.