Professional boxers are notorious for not knowing when to say when. The list of once great pugilists fighting way past their primes is endless and includes everyone from Oscar de la Hoya and Mike Tyson to Roberto Duran and Sugar Ray Robinson. The definitive movie on the subject is Rod Serling's 'Requiem for a Heavyweight.' I highly recommend renting it from Netflix.

Boxers stick around for a variety of reasons. Many rose from the ranks of poverty and, once flush with the sweet smell of success, squander their winnings on fast cars, loose women and an exorbitant lifestyle. Faced with mounting bills and lightened wallets, the battered boxers step back into the ring against younger, faster and stronger opponents. Some survive. Others, like Ali, pay a heavy price.

Another big reason for fighting past one's prime is the uber rush that comes from performing in front of adoring fans. Adulation is the meth amphetamine of professional athletes. Which has to be the reason why Brett Favre is still bouncing around on the gridiron.

Favre was clearly past his prime in his final season with the Green Bay Packers. One could argue that he single-handedly lost the NFC title game to the Giants that season. And, his performance with the Jets last year should have convinced everyone, including Favre, that he was done.

Besides the physical risks associated with playing past one's prime, these ill-considered moves do significant damage to the athlete's image and reputation.

I'll always remember the 40-something Willie Mays stumbling and falling in a vain attempt to catch a fly ball in the 1973 World Series. Mays' legs were shot, but he couldn't face retirement. So, he embarrassed himself.

Favre needs to hang up his spikes. The longer he sticks around, the more damage he'll do to his image and reputation.