Most retirees look forward to relaxing at home, but Bill Harrelson, 69, wanted to see the world. All of it.

The former pilot from Fredericksburg, Virginia, retired 15 years ago, but he just couldn't stop flying. So, last month he decided to embark on the journey of a lifetime.

Harrelson took the single-engine Lancair IV he built and flew it around the entire world. It was no easy feat — the retiree took the 121-hour, 21,000-mile trip solo. It was just him, his craftsmanship and his piloting skills up in the air for about eight days.

Bill Harrelson took a 21,000-mile solo trip in the single-engine Lancair IV he built himself. CBS affiliate WUSA-TV

"There's no doubt about it — it's risky," Harrleson told CBS affiliate WUSA-TV. "It's not a particularly safe operation to undertake." The pilot had flown around the world before, around the poles.

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This time, he flew westbound, against the wind. This record has not been challenged since 1961, but Harrelson made the daring attempt and succeeded. "It was an exercise in dealing with adaptation and change," he explained.

Harrelson left from Ontario, California, on December 8 and returned eight days later, making only four stops in Hawaii, Indonesia, South Africa and Puerto Rico along the way, according to WUSA-TV. To ensure he could make the long flight, almost all the extra space in the plane was filled with fuel.

"It's a small planet and people are pretty much the same everywhere," Harrelson said. "We have a lot more likenesses than we do differences." WUSA-TV

There were 30-hour legs where Harrelson flew over nothing but water. He had issues with his engine, radio and even flyover permits from the island nation Mauritius. Harrelson, however, persisted. And he learned a lot from this unique journey.

"It's a small planet and people are pretty much the same everywhere," Harrelson said. "We have a lot more likenesses than we do differences." He hopes his solo trip inspires others to expand their horizons — no matter how old they are.

"Everybody should not be afraid to do something they haven't done before," he said. "Take a step into uncharted territory, even if it's just uncharted for them, and make adventure a part of your life."

The trip is now under review by the Fédération Aéronautique Internationale as a new record in the plane's weight class, Harrelson said.