For Michael Clinton, this harsh winter was a stroke of luck. While most New Yorkers huddled inside, the president-marketing and publishing director of Hearst Magazines went on 20-mile runs during storms.

Why would he do such a thing? To prepare for a marathon -- in Antarctica. "It was a good winter for training purposes," he said March 4 from Buenos Aires, where he was preparing to continue his journey south. Mr. Clinton completed the 26.2-mile race in Antarctica four days later, fulfilling the goal he set five years ago to run a marathon on all seven continents.

Colleagues know the many miles he logs on his running shoes. "I solve a lot of business problems and make a lot of decisions," he said of his long runs. "It's become my therapy of choice."

The seven-continent goal began in 2009, after Mr. Clinton completed the London Marathon with his sister. The following year they ran another in Buenos Aires. "It mushroomed into a life challenge," he said. "Thank God for frequent flier miles."

Together, Mr. Clinton and his sibling ran marathons on Australia's Gold Coast; Mount Kilimanjaro in Africa; Mongolia in Asia and Philadelphia. They planned to run the New York marathon in 2012, but it was canceled because of Hurricane Sandy. Harsh conditions also scuttled a South Africa marathon on race morning. The Mongolia race proved most difficult. It took place in a wooded, mountainous region where mile markers were painted onto trees and rocks. "I didn't know what I was getting myself into," he said.

He braved Antarctica's marathon, run on packed snow or ice in everyday running shoes, without his sister. Just reaching the continent is a feat: It requires several plane rides to the southern tip of Argentina, where the runners board a Russian ice breaker for a multiday boat ride south.