Dave Scott and Mark Allen suffered immensely during the 1989 Ironman, the race remembered as Iron War for the awe-inspiring duel that took place between these two legendary athletes within it. In fact, Scott and Allen probably suffered more than any of the 1,284 other competitors in the race, and that is probably why they finished the race more than three miles ahead of any other competitor.

Allen's most excruciating moments came about halfway through the marathon, when Scott, who had been towing Allen along since the first strokes of the swim almost seven hours earlier, threw down a vicious surge that threatened to once again finish off the man who had lost to Scott five times previously at Ironman.

"I responded, but barely," Allen later wrote of those moments. "My reserves were reaching their limit? This is too much. My legs are killing me."

Despite these torments, Allen found a way to rally and win the greatest race ever run. Which means Dave Scott ultimately suffered even more. Soon after Scott crossed the finish line 58 seconds behind Allen, a journalist asked the runner-up how the race had felt.

"I'm not sure I want to feel that again," he said.

Accepting the degree of suffering that Dave Scott and Mark Allen bore in their Iron War requires exceptional motivation. What motivated Scott and Allen to embrace the agony they did in their epic showdown? It certainly wasn't money. The prize for winning the 1989 Ironman was a meager $20,000. The second-place finisher took home $8,000.

One of my goals in researching my newly published book about Iron War was to discover what motivated Dave Scott and Mark Allen to reach so deep in that race. I learned that, while each man had his own personal motivations, perhaps the greatest motivation was shared—and not only that, but was the same motivation that draws every Ironman participant to the challenge. Scott and Allen just had more of it.

In 2008, a Canadian-born sociologist named Michael Atkinson published a paper titled, "Triathlon, Suffering, and Exciting Significance." In it, he argued that the tremendous amount of suffering that all triathletes experience in training and, especially, in races is not a negative price that participants pay in pursuit of the rewards of the sport; instead, that suffering is itself the primary reward.

Atkinson argued that the comforts and conveniences of modern life have come to pamper us so much that much of the excitement has been drained from our daily existence. Our bodies are so coddled that we crave physical challenges. On top of that, we have grown mentally soft, and we know it and vaguely despise ourselves for it.

Triathlon represents a way to put some excitement back into our lives, to toughen us mentally, and to boost our self-respect. The sport delivers these rewards by affording us an opportunity to overcome great suffering. The prize that every triathlete seeks above all others is what I call the finish-line feeling—that tremendous feeling of satisfaction that comes when we complete a race and conquer the internal weakness that tempts us to quit.

It is no accident that the event that caused triathlon's popularity to explode was Julie Moss's famous crawl to the finish line of the February 1982 Ironman. We who watched it—the susceptible among us, at least—felt a powerful urge to suffer as she did, and to bravely defeat our suffering, as Moss did hers.

The more you suffer in a triathlon, the better the finish line feels. While the finish-line feeling is the ultimate motivator for the suffering we subject ourselves to in races, other motivators may inspire us to suffer even more, which enhances the finish-line even more, which boosts our willingness to suffer still further. The opportunity to win is one such motivator. Competition is another. Competition against an arch-rival works even better. A state of peak physical readiness—having your best day and knowing it—is still another.

In the 1989 Ironman, a perfect storm of circumstances conspired to make Dave Scott and Mark Allen willing and able to endure as much suffering as any athlete ever has in competition. And that's one of the reasons both men redefined the possible on that unforgettable day.

Push your limits at a race.

Matt Fitzgerald is the author of Iron War: Dave Scott, Mark Allen & The Greatest Race Ever Run (VeloPress 2011) and a Coach and Training Intelligence Specialist for PEAR Sports. Find out more at mattfizgerald.org.