"I just didn't think I would make it. I just didn't think I would," Hahn told KETV. "It's hard to believe I could get this far along."
He did. Hahn celebrated his centennial birthday Sunday at the Woodbridge Senior Living Center in Omaha. Born in Mapleton, Iowa, Hahn served with the Army Signal Corps during World War II, helping to transport communications equipment for radio relay stations, according to KETV.
"That was a long ride. All the way from the European theater, all the way from Africa, out into Malta, (and) around Sicily, Italy, France and Germany," Hahn told the television station.
After the war, Hahn worked for the U.S. Postal Service, later moving to Nebraska to be closer to his family, KETV reported.
Hahn said he received birthday cards from government officials and President Donald Trump.
"It's unbelievable," Hahn told the television station.
Hahn said his secret to living to 100 is to "be kind, be careful, and be cautious," KETV reported. He also makes clocks out of steering wheels, tends a tomato garden and enjoys board games.
"It amazes me that he just keeps going and going," Hahn's son, Gary Hahn, told the television station. "He's sharp and he likes to keep busy."