"I realize not everyone can enjoy good health, but it's still possible to do things when you're quite old," said 97-year-old Martha Tolles. "That's the good news."

Tolles, who gained success as a children's book author in her 40s — selling more than 2 million copies of her "Katie" series through Scholastic and other publishers — recently came out with her first novel for adults: "Love and Sabotage," set during World War II.

Though never a full-time writer, she has persisted through the years, adapting her formats to find new audiences for her work. She's stayed in the writing game, moving from children's short stories and children's books to memoir essays and now, a novel for adults. The part-time Palo Alto resident even enrolled in a writing class at Stanford Continuing Studies in 2008 when she was in her mid-80s.

"You hear of people who suddenly discover something they love, whether surfing, sewing, singing or whatever," she said in a recent interview. "And I found something I loved, which was writing for kids."

Tolles said she stumbled on writing inadvertently while in her 30s. She was raising six children in southern California with her lawyer husband when she experienced back trouble serious enough to require surgery.

"I had to hire two different gals to come in and run the show for me," she recalled. "There I lay. There was one television but it was downstairs and I was upstairs and they needed it downstairs. I got very bored, even though I love to read. So one day I thought, 'Maybe I'll just try writing a story.'"

She wrote a few and was buoyed by early success, selling stories to the popular children's magazines "Jack and Jill" and "Highlights."

"As soon as my back got better, I went off to Pasadena City College and enrolled in night writing classes and just loved the whole thing," Tolles said. "I had these (magazine) sales and I think the teacher said to me something about, 'Have you thought about writing a book?' So then I did think of it."

Inspired by her own children — one daughter and five sons — Tolles's first title was "Too Many Boys," the story of Katie, who is vastly outnumbered by the boys in her neighborhood. First published in 1965, it was later republished by Scholastic under the title "Katie and Those Boys." It led to several other books in the Katie series — some of which are now being reissued as e-books — "Katie's Babysitting Job" and "Katie for President."

"When I wrote 'Too Many Boys' my daughter was about 11," Tolles recalled. "After I sold it, I was at the table one night looking terribly proud and pleased. She said, 'You know, mother, you're not really an author, you're just a mother who wrote a book.'"

Eventually Tolles penned at least eight children's titles published by Scholastic, reaching sales of 2.3 million. Later she wrote stories for the children's page of the Los Angeles Times, three of which were published as paperbacks.

When editors lost interest in her children's books, Tolles adapted. "Styles change in books, just like in clothing and everything else." Eventually, "everybody wanted to read Harry Potter instead of everyday realistic fiction," she said.

Switching gears, she mined her memories to produce what she calls "looking back essays" and scoured the web to find publishers. Magazines with names like "Good Old Days," "Dame" and "Skirt" published the reminiscences — about being late to her own wedding on a Corpus Christi naval base in 1944 or about her early days as a housekeeper. Another essay, "While Lying Down on the Job," explained how she launched her writing career while in bed.

Tolles and her husband became part-time residents of Palo Alto about 15 years ago, when they arrived to help their daughter at the time of the illness and death of their son-in-law, physician Alex Tseng. Their daughter Cynthia Tolles Tseng passed away a few years later in 2010. Tolles has continued to spend time in Palo Alto, though her primary residence since 1948 has been southern California.

After her husband of 63 years died in 2008, she enrolled in the writing class at Stanford, where she developed the World War II novel. The story line echoed that of her own life in the 1940s — a recent graduate of Smith College working as a newspaper reporter with a fiance who's a Marine fighter pilot in the Pacific.

"I think writing it helped me because so much of it was about our life together," she said. "In real life, I was married; in the book, I was engaged. In both cases it was Edwin Roy Tolles who was the fighter pilot. (The war) was an interesting time because women were getting jobs they'd never had before." The novel, "Love and Sabotage," was published in 2018 by Speaking Volumes press.

Tolles continues to participate in her writers' group, which grew out of her Pasadena City College writing classes in the 1970s. Members gather weekly to read and discuss one another's manuscripts.

She recently sent four boxes full of papers documenting her career — including drafts, correspondence with editors and fans and interviews — to the archives and manuscripts collection at Smith College, where graduated with the class of 1943.

Tolles said the problems with her back cleared up years ago. "I wouldn't play golf and I don't lift heavy things, but otherwise I'm just fine," she said.

She reflected on the mixed emotions of aging in an essay, "This Is What It's Like To Be 90," published by Dame magazine in 2015: "Funny how I've begun to feel boastful about my age after years of desperately trying to hide it," she wrote.

"And so here I am, missing my loved ones and dear friends, trying not to feel lonely, especially without my husband of 63 years — yet sheepishly proud I'm here. Because I am so old, people don't expect much of me either. When walking with a younger friend the other day, she said, 'Look at you. Aren't you amazing? You can still walk!' Well, yes, I can and I'm still enjoying it. Sort of."