Cheltenham: Being stuck at home didn't stop a British man from running an outdoor marathon during lockdown.

James Campbell, a former professional javelin thrower, spent his 32nd birthday on Wednesday doing 6-meter (20-foot) shuttles from one end of his small backyard to the other after promising to run a marathon if one of his Twitter messages received 10,000 retweets.

By the time Campbell completed the marathon in just over five hours, he had raised more than 18,000 pounds ($22,000) for Britain's National Health Service to help battle the coronavirus pandemic.

The effort -- labelled the #6metregardenchallenge -- was live-streamed, with former England soccer great Geoff Hurst among the viewers. Neighbors poked their heads over the backyard fence to give Campbell encouragement.

Campbell ran across a patch of grass, some stones and a small patio in 6-meter (20-foot) stretches. He calculated he would have to traverse his yard at least 7,000 times to reach 42.2 kilometers (26.2 miles).