Here’s the safest bet in North America this week: The most powerful advocate of motorcycle and bicycle helmets will soon be a 24-year-old named Ben Roethlisberger of Pittsburgh, Pa.

Hold it. Let me amend that, given that we are talking about a person who is often hurled through the air for a living and who thinks he is invulnerable. It only stands to reason that a man who wears a helmet at work, who calls the plays his coaches send into the huddle, and who hires sober and mature people to advise him on his finances and endorsements will listen to the sober and mature advice he will almost certainly be given to make things right with the fans and with his teammates: Become the poster child for protective helmets. Because that’s the answer to the question that almost certainly has been haunting Mr. Roethlisberger (with apologies to The Heads, who put the phrase to music): How do I undo the damage I have done?

Contrition is convincing, remarkably so. There’s no more convincing an advocate for drug-free living than a former user who has hit bottom. There’s no more credible a crusader for fitness than someone who has been felled by a heart attack. Who is the most prominent advocate for slimming down? Mike Huckabee, the governor of Arkansas, who once was technically obese. Who made one of the most poignant public-service announcements about the danger of cigarettes? Yul Brenner, who died of lung cancer.

Regret is a powerful motivator, as two of America’s greatest preachers, Waylon Jennings and Willie Nelson, have argued. Don’t let your babies grow up to be cowboys. Or smokers. Or binge-eaters. Or cocky motorcyclists who think a baseball cap worn backward is protection enough from dangers off the field.

Some of the most searing testimonials of regret are on the Web site of the Texas Department of Criminal Justice, which chronicles the last statements of death-row inmates before execution. Here is an excerpt from the remarks of Robert Dale, executed seven months ago for murder: “I would like to apologize to the victim’s family and (for) all the grief I have caused them.”

Now here’s a sentence I never thought I would type: A good role model is Michael Milken. But the truth is that Mr. Milken has sworn off both junk bonds and junk food. Just out of prison serving a sentence for securities fraud, Milken discovered he had prostate cancer. He became a vegetarian and an evangelist for healthy eating, urging everyone who will listen to eat five to nine servings a day of fruits and vegetables without sauce or dressing and to load up on soybeans. That’s better than some of the investment advice he used to hand out.

Another king of contrition was John D. Profumo, who died this year. Profumo, the one-time British secretary of state for war, was at the center of one of the greatest sex scandals of Cold War Britain, having had an affair with a showgirl who also had an affair with the Soviet naval attache. Profumo resigned and went to work, quietly and selflessly, with charities in London’s East End.

And today, the longest-serving senator in American history, Robert C. Byrd of West Virginia, toils in the Capitol to build a legacy that somehow will overshadow what he calls “the greatest mistake of my life,” his youthful membership in the Ku Klux Klan in the 1940s.

But one of the most powerful motivations for Ben Roethlisberger and his possible new role comes from a complete innocent, as the Steelers quarterback may consider himself. That is James S. Brady, who was Ronald Reagan’s White House press secretary. Mr. Brady suffered a gunshot wound to the head in the 1981 attempted assassination of the president, and, with his wife, Sarah, has since become a prominent advocate for handgun controls.

“A life-altering event awakens you,” Sarah Brady, chair of the Brady Center to Prevent Handgun Violence, said in a conversation this week. “It’s almost a responsibility to speak out, to save others from having to go through what you have gone through.”

These examples all should serve as inspiration for Roethlisberger, who after all has a lot of time remaining for contrition. But since quarterbacks are motivated by statistics, he will almost certainly be told that the number of motorcycle deaths and injuries is increasing – and that cyclists without helmets are three times more likely to suffer brain injuries than those who wear them.

There is, to be sure, no helmet law in Pennsylvania or in 29 other states. But that doesn’t mean cyclists in those states can’t wear them. They can, and Roethlisberger can help. “With his reputation, his age, and the fact that he’s an avid motorcyclist, whatever he said would resonate within that community,” says Rae Tyson, spokesman for the National Highway Traffic Safety Administration and a longtime motorcyclist himself. “He could make a life-or-death difference. If you’re wearing a helmet – they are 37 percent effective in preventing a fatal injury – you have a much better chance of surviving, and surviving without a debilitating injury.”

Mr. Roethlisberger could do a commercial, be on billboards or testify before state legislatures. He could have an impact far greater than the federal government, which has been specifically prohibited by Congress for getting involved in state legislative battles on motorcycle helmets. If he is shy, or reluctant to make a public spectacle of repudiating his own words, he could simply be photographed putting on a helmet. People will get the message. They appreciate a quarterback who can call an audible when circumstances change.

For Roethlisberger, who has buffed his I’m tough image by saying he doesn’t need to wear a helmet, the decision will come down to Steelers pride vs. a young man’s pride. He knows what the right decision is. Bet on it.