George Foreman, left, hits Michael Moorer in the face with...

George Foreman, left, hits Michael Moorer in the face with a left during the second round of their heavyweight championship fight at the MGM Grand in Las Vegas on Nov. 5, 1994. Credit: AP/Lennox McLendon

The next time you hear someone say that people can’t change, tell them about George Foreman.

Tell them about the teenage punk who used to travel from his home in Marshall, Texas to Shreveport, Louisiana to mug people. Tell about how he became a man who gave millions of dollars to charity and in his non — boxing life served as pastor to a small, devoted religious congregation.

Tell them about the surly young champion who specialized in intimidation, of his opponents, the media and the public, and how he developed into a smiling teddy bear who sold sandwich makers, provided goofy TV fight commentary and was an affable, eagerly sought interview.

Tell them about the one-dimensional slugger who needed to be talked out of quitting in his first major Madison Square Garden fight, and how he matured into a relaxed, disciplined fighter willing to walk through fire to win a fight, as he did in his remarkable victory over Michael Moorer.

Tell them about a boxer who began his career wanting to be feared like Sonny Liston and endedit as beloved as Muhammad Ali. His first career was a reign of terror. His second was a sitcom.

In his prime, George Foreman was more fearsome than Mike Tyson. In his dotage, he seemedas harmless as Barney the dinosaur. In truth, he was equal parts both.

The life story of Foreman, who died on Friday at age 76, was the kind of story that could not be believed if it had not happened before our very eyes.

What Foreman accomplished is not only the greatest comeback in boxing history, but indisputably the greatest comeback in all of professional sports.

His 10th-round KO of Moorer, accomplished with a single right hand that traveled no more than six inches, is the most shocking, exhilarating and yes, moving event I ever covered in 37 years of sportswriting. That run included dozens of world title fights.

None of them could compare with the moment when Foreman, swollen, exhausted and having lost every second of the fight to that point, sent Moorer to the canvas to regain the title he had lost to Ali in what was called Zaire 20 years before.

In fact, Foreman was a pivotal figure in three of the most spectacular and unexpected knockouts in the history of boxing. The first was his upset of the previously-unbeaten and believed to be unbeatable Joe Frazier in Kingston, Jamaica on Jan. 22, 1973.

The second was the equally shocking KO Foreman suffered at the hands of Ali, a fight expected to be so one-sided that members of Ali’s own camp feared for his safety, and even his life. The despair of that loss began Foreman’s descent into the abyss where he would spend his next decade.

The third, of course, was the Moorer fight.

Launched at first, he said, to raise money for the youth center he had established in Houston, Foreman’s comeback was considered a sideshow attraction. He was fat and slow and he shambled around the ring with his arms outstretched like Frankenstein’s monster. Often, his punches looked like someone doing the Australian Crawl. He fought a succession of bums who came in waiting to be carried out. All his fights seemed to lack was a laugh track.

But something had happened to Foreman in those 10 years of self-imposed exile. As he lost the chip on his shoulder, he seemed to find himself. No longer did he come into the ring looking — no, needing — to end the fight in a hurry because he wasn't sure how long he would last. Now he settled in, conserved his energy, and refused to give in to the discouragement that comes with exhaustion.

The KOs kept piling up. He was beating better and better fighters. Dwight Muhammad Qawi, a former light-heavyweight champion, fell in seven. Bert Cooper, a huge puncher who had once dropped Evander Holyfield, fell in two. Then came Gerry Cooney, who had gone 13 with Larry Holmes.

By then, Foreman had honed his Fighting Preacher routine to a fine edge and spent most of his time in Atlantic City before the Cooney fight kissing babies and bantering with the crowd who came to his “training sessions.’’

But under the comedy routine, there was a shrewdness to Foreman that he kept hidden from the crowd. The night before the fight, I had dinner with Gil Clancy, who had trained Foreman in his first career bout but after a falling-out, was now training Cooney. Clancy was buoyant and optimistic on the eve of the fight, encouraged by Foreman’s apparently lackadaisical approach.

“If Foreman wins this fight,’’ he told me, “It will set back boxing training 100 years.’’

But as we walked back to our hotel, we heard what sounded like fists thudding against a heavy bag in one of the ballrooms. Curious, we poked our heads in — to see Foreman pounding away in an intense 11 p.m. workout. Right then, Clancy realized that Foreman, the hapless victim of Ali’s rope-a-dope, had now rope-a-doped him.

The next night, Foreman stretched out Cooney in 2 with an uppercut that could have dropped Secretariat. Nobody was laughing at Foreman anymore. We were all laughing with him.

Never would have happened 20 years before. But then, people do change. Just look at George Foreman.

Wallace Matthews is a former Newsday sports columnist and longtime boxing writer.