This senior citizen is booked.

A 99-year-old World War II veteran proved that it’s never to late to do what you love after embarking on a career as a children’s book author. Now, with two titles under his belt, the nonagenarian is earning the admiration of a new generation of young readers.

“Reading is a foundation for all other learning,” Sam Baker, 99, told Fox News of the inspiration behind starting a new vocation at nearly a hundred years old.

His was a story of fatigues to fountain pens: The Scottsdale, Arizona, native enlisted in the Marine Corps at 19 in 1942 — several months after the Japanese attack on Pearl Harbor. After leaving the service in 1947, Baker joined the US Coast and Geodetic Survey — now the National Oceanic and Atmospheric Administration, also known as NOAA, where he worked for three decades until he retired.

Then, at 95 years old, Baker decided to become a writer — an idea that was sparked after he purchased his first computer, Military.com reported.

“My son called and said, ‘Dad, now that you have a computer, why don’t you write down the stories you told us when we were kids, for your granddaughter?’ ” the elderly bookworm told the military paper of his new vocation’s genesis.

Deciding to honor his kin’s request, Baker typed his first ever children’s book, “The Silly Adventures of Petunia and Herman the Worm,” which was published in 2018. The opus was, per his son’s suggestion, based on the stories he used to tell his kids about a worm named Herman.

The soldier-cum-scribe followed that up in 2020 by publishing his second book, “Oscar the Mouse,” which was inspired by a “white rat” someone gifted him as a kid.

“She and I used to have a good rapport,” Baker reminisced. “But my mother wouldn’t let me take her in the house, so I had to build a cage for her outside.”

The author decided to make her a mouse in the story as “people accept mice over rats,” said the author. Baker’s childhood pet is also the subject of his third book, which he said will be published in “early to mid-2022.”

The veteran’s accomplishments as an author are particularly impressive given his own struggles with reading while growing up. As Baker was only taught sight reading, his journey to literacy was quite difficult — and the senior reportedly didn’t even master phonics until adulthood.

Still, Baker’s passion for reading flourished in the ninth grade, when he was assigned a dozen book reports in one year.

The prolific children’s author ultimately hopes his works will instill a love of the written word in the younger generations.

“Both of my books were written with two basic goals: to encourage children of all ages to learn to read and to impart an important life’s message of acceptance,” said Baker. “If my book can encourage children to become avid readers, I will feel that I have been a great success.”

In another age-defying literary success story from February, an 8-year-old Idaho boy snuck his homemade comic book into the local library — and got it published.