Michelle Obama told Oprah Winfrey that 'What do you want to be when you grow up?' is the worst question an adult can ask a kid.

She was explaining the title of her new memoir, "Becoming" — growing up is not finite, she said; one is always becoming who they are meant to be.

"Becoming" details Obama's journey and is filled with personal revelations from her childhood, careers, and motherhood.

Michelle Obama has earned a reputation as a soundboard of advice for women and young people, and this time, she's got something to say about a popular question often posed to children.

"A question that adults ask kids — I think it's the worst question in the world — is 'What do you want to be when you grow up?'" she said in a recent interview with Oprah Winfrey published in Town & Country.

"As if growing up is finite. As if you become something and that is all there is," Obama said.

She was explaining to Winfrey how she settled on the title of her new memoir, "Becoming," set to hit bookstands on November 13. The word summed it all up for her.

Obama said she doesn't know when the next step will be and that's something she often tells young people. "You know, all young women probably have some magic number of what age you'll be when you'll feel like a grown-up," she said. "Generally, when you think your mother will stop telling you what to do."

Read more: Michelle Obama opens up about the first time she saw Barack and what their first kiss was like

She added: "But the truth is, for me, each decade has offered something amazing that I would never have imagined. And if I had stopped looking, I would have missed out on so much. So I'm still becoming, and this is the story of my journey. Hopefully, it will spark conversations, especially among young people, about their journeys."

In "Becoming," Obama chronicles her journey from her childhood in Chicago to her time spent in the White House, while juggling her career as a lawyer, role as First Lady, and motherhood.

It's full of personal revelations, including how she struggled with a miscarriage and infertility, how she and Barack have attended marriage counseling to make their relationship stronger, and how she'll never forgive Donald Trump for promoting the false birther conspiracy and putting her family at risk.

Winfrey made "Becoming" the next pick for her book club, calling it "well-written" and "inspirational," reported the Associated Press.