Story highlights He left high school early to join the Navy in World War II

It was his lifelong dream to earn a high school degree

(CNN) It's never too late to graduate.

That's the lesson World War II veteran Milton Mockerman shared with the Kalkaska High School class of 2017 with whom he graduated on Saturday.

Mockerman, 89, received an honorary diploma from the school and participated in its graduation ceremony in Kalkaska, Michigan, fulfilling his lifelong dream of earning a high school degree -- 71 years later than expected.

Milton Mockerman served in the Navy during World War II.

"We got a phone call from Milton Mockerman wondering if there were any classes he could take to finish his graduation," Kalkaska High School Principal John Sattler told CNN.

Sattler soon learned that Mockerman had forged his birth certificate and left high school early to join the Navy during World War II. After serving in the Navy for two and a half years, Mockerman returned home to Michigan and needed to find work. He found a few odd jobs before going to work on the railroad for 31 years.

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