David Becker/Associated Press
The fighter's itch is a hard one to scratch.
The fight is a challenge unlike any other, built on lifelong preparation boiled down to a training camp of only a few months and a high-adrenaline problem-solving exercise of only a few minutes.
It's not hard to understand why it is, based on that intensity of experience and the fact a fighter's whole life revolves around the routine of preparing for it for as long as they compete, that athletes who retire rarely stay retired for long.
Randy Couture left at 42, only to return at 43 and fight eight more times across two weight classes.