Dave Obelkevich’s first experience with the New York City Marathon was in 1973, when it had fewer than 400 entrants and took place entirely in Central Park. He was on the west side of Manhattan near 100th Street when a pack of runners in bibs flew by. He asked a few onlookers what was going on. “It’s the marathon,” they said.

A recreational runner himself, he was both impressed and intimidated by the lead runners’ speed. He knew he couldn’t keep up with them for 26.2 miles, but he figured he could probably finish one of the four loops of the park at a respectable pace. So, on their final lap, he jumped in and finished in 43 minutes. After that, he immediately signed up for the following year.

Obelkevich admits that it took a couple of years for his training to gel. In the months leading up to the 1974 race, he did just one six-mile training run a week. “I took six days off,” he says, laughing.…