NORTHGLENN, Colo. (CBS4) — WWII veteran Lyle Jackson celebrated his 100th birthday at the Elks Lodge in Northglenn on Saturday surrounded by friends, family and service members.

(CBS)

People at the party watched a slide show honoring Jackson’s life and enjoyed a cake with a picture of him in uniform.

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(CBS)

He says he spends his day writing about his time in the air force and when he worked in the government. He’s already written three books.

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His secret to a long happy life: “Be honest, be straight and have determination. A lot of determination. Whatever you do, make it better than the other guy.”

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Lyle Jackson (CBS)

As part of the celebration, the Denver Army Recruiting Battalion sent some soldiers in uniform to show appreciation for his service.

(CBS)