Will Rogers catches something most proverbs about moving on miss: the *arithmetic* of regret. He's not merely saying "don't dwell," but rather diagnosing how yesterday becomes a thief—a sneaking, compound loss where one bad day doesn't just sting once, but bleeds into the next morning's energy and choices. A person who replays a failed meeting at 3 p.m. has already spent two hours of productive work watching it unfold in their mind; they've paid twice. What makes this particular wisdom stick is the verb *use up*—it suggests yesterday has a currency, a limited budget we're foolish enough to loan it, when we might spend that same emotional capital on what's actually in front of us.