Before Barack Obama became president of the United States 10 years ago, he had an important task to complete — getting his wife’s approval to run for the White House.

In a revealing new memoir published Tuesday, former first lady Michelle Obama shares her thoughts preceding the historic November 4 night in 2008. She writes that she never expected America to elect a black man for president. Though she loved Barack Obama and “had faith in what he could do,” she writes that part of why she let him run is because she believed he wouldn’t make it too far in the race.

“I said yes, though I was at the same time harboring a painful thought, one I wasn’t ready to share: I supported him in campaigning, but I also felt certain he wouldn’t make it all the way,” Michelle Obama says in Becoming. “He spoke so often and so passionately of healing our country’s divisions, appealing to a set of higher ideals he believed were innate in most people. But I’d seen enough of the divisions to temper my own hopes.

“Barack was a black man in America, after all. I didn’t really think he could win.”

Eventually, though, other factors also contributed to Michelle Obama agreeing to Barack’s presidential run: She knew her husband was surrounded by a team of “good, smart people.” And she believed he would be a kind president who would better the lives of millions of people — and it was worth putting her own needs, and the needs of their daughters, aside in service of that vision.

Barack Obama, then a senator from Illinois, went on to win the Democratic bid for the presidency and the final match against late Sen. John McCain. He carried 28 states and the District of Columbia, also winning the popular vote with 9.5 million more votes than his Republican opponent.

Following his victory on election night 2008, Barack Obama took the stage at Grant Park in Chicago to deliver a passionate speech about America being “a place where all things are possible,” thanking his wife for the support she gave him along the journey of the race.

“I would not be standing here tonight without the unyielding support of my best friend for the last 16 years, the rock of our family and the love of my life, our nation’s next first lady, Michelle Obama,” he said.