His trainer, Joe Goossen, told him.
As respected a boxer as Sugar Ray Leonard told him.
But still, middleweight Michael Nunn could not seem to change his style enough to get more leverage, and thus more power, behind his punches. He just couldn't shift his body and his hips into the lefts and rights he threw at opponents. As a result, he was connecting with his knuckles rather than the meaty part of his fist. Some of his punches would better be described as slaps.
That's not to say he was helpless in the ring. Far from it. Nunn has won all 14 of his professional fights, 10 by knockout.
But his handlers, the Goossen family of North Hollywood, knew that if Nunn continued to employ his style, he might get into real trouble as he continued to move up as a middleweight. They didn't want to just sit around and wait for the ax to fall.
So instead, they put the ax in his hands.
When Nunn completes his normal training routine these days--eight to nine rounds of sparring, jumping rope and hitting the punching bag--he marches out in front of the Ten Goose gym in North Hollywood, puts on safety goggles and proceeds to take 100 swings at a pile of wood with his trusty ax.
"We've seen great results," Joe Goossen says. "He's getting all of his body weight into his punches now. Before, he had a tendency to break off halfway through a punch, not turn his left hand over. By swinging the ax, it's forcing him to rotate his hips and turn his shoulder. In some ways, it's better than hitting the bag. When you do that, you tend to ding some of your punches. With the ax, you've got to hit hard every single time.
"Michael has knocked down several of his sparring partners, including a 200-pounder who never came back to our gym.
"The wood-chopping technique is nothing new. Old-timers have done it for years. Rocky Marciano probably chopped down every tree in upstate New York during his career."
Nunn won't have to wait long to try his new technique on something more animated than a log. He'll be in the ring Monday night at the Reseda Country Club where he'll take on Felipe Vaca (37-9, 22 knockouts) of Mexico in a 10-round main event.
Five other bouts are also on the card with the first fight scheduled for 8:15.