Being stuck at home didn’t stop a British man from running an outdoor marathon.

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.