Arguably the most important tool to keep you running over the years is appropriate shoes. Koen Wilssens, 30, operates a chain of running shops called Runners Service Lab in Belgium. His selling point is an indoor track of some 40 meters that scans the foot as it hits the surface to determine the type of shoe one should wear. (Ms. Radcliffe appeared for the opening of the newest location, just outside Antwerp, because that’s where she buys inserts for her Nikes.)

Mr. Wilssens estimates that 50 to 60 percent of people wear the wrong type of running shoe. Not everyone has access to a shop like his, but many metropolitan areas have shops that offer video analysis. The right shoes won’t guarantee you first place, but the wrong shoes guarantee you a short-lived running career.

Thom Gilligan’s livelihood is running. A former competitive racer, Mr. Gilligan, 62, founded Marathon Tours & Travel in 1979 in Boston, which takes groups to races as far-flung as Kenya and Antarctica. For him, the hardest part is “keeping the passion going.” His solution is to set achievable goals.

Mr. Gilligan’s personal goal is the Bermuda Triangle Challenge, a January event that he’s entered 33 of the past 34 years. It consists of a mile race on Friday, a 10-kilometer run on Saturday, and a half or full marathon on Sunday. “Any person who has been fit all their life I think realizes the intangible benefits of having a healthy lifestyle,” he says. “It’s addictive.”

And sometimes, success is simply a result of years of experience, as it is for Heiko Schaefer. Mr. Schaefer, 72, is busy trying to qualify for the Six Foot Track Marathon , a 45-kilometer race in the Blue Mountains west of Sydney.

Mr. Schaefer began running for fun 21 years ago with his son. In 2000 he joined a running club, the Sydney Striders, and a few days afterward ran in the Host City Marathon along the course designed for the Olympics that were held in the city later that year. “That was the day I caught the bug,” he recalls. He drew on the knowledge of his teammates and read everything he could about running.

In April, he won the over-70 age group at the Canberra Half Marathon with a time of 1:47:32. As his name was called and he approached the podium to collect his prize, he was expecting a trophy or a medal. Instead, he received Paula Radcliffe’s book “How to Run.” “There was nothing in there that I didn’t already know,” he joked.

All this advice is worth heeding. I ran my first marathon in Rome in 2004, when I was 34. The race started at the Colosseum, went past the Vatican as the pope was preparing Mass and ran through Piazza Navona. As spectacular as those sights were, one of my most vivid memories was of the older runners, many in their 50s and 60s and 70s, passing me as I began to struggle at Kilometer 30.

This weekend, at the age of 41, I will be joining Ms. Radcliffe and Mr. Gebrselassie in the Berlin race, though thousands, if not tens of thousands, will cross the finish line between them and me.

I am fitter and faster than I was in Rome, which is a good feeling. But much of my satisfaction stems merely from being able to keep running, because a lot can go wrong along the way.

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By TOM SIMS