Michelle Obama on whether she thought her husband could win; bruising campaign to the White House Former first lady Michelle Obama speaks to "GMA" co-anchor Robin Roberts.

Michelle Obama shared with "Good Morning America" co-anchor Robin Roberts some key advice she'd give her pre-White House self, if she had the chance, as the two sat down to discuss her memoir, "Becoming."

"You know the hard parts were the things that I expected," Michelle Obama told Roberts in the exclusive interview.

"That it was gonna be hard, you know? Being the first black anything is gonna be hard."

"So much of this country lives in isolation and we just don't know each other. ... There were people who didn't know what a black woman was and sounded like. And, so I knew that was gonna be a challenge, that I'd have to earn my grace -- and I experienced that on the campaign trail," she said.

It was the campaign trail that tested her self-esteem.

In the summer of 2004, Barack Obama was already a rising star when he was asked to speak at the Democratic National Convention. By 2008, after a meteoric rise to fame, the senator announced his candidacy for president.

Michelle Obama said that although she'd given him her blessing to run, she didn't think he'd win.

And, when she saw him on the cover of Time magazine in October 2006 with the headline, "Why Barack Obama could be the next president," she looked away.

She didn't even want to see it.

"I think I did what a lot of black folks were doin'," she told Roberts. "We were afraid to hope because it's hard to believe that the country that oppressed you could one day be led by you, you know?"

"I mean, my grandparents, you know, lived through segregation," she continued. "My grandfather, his grandfather was a slave, you know? So this, these memories were real. And they didn't think the country was ready. And, and so my attitude was a reflection of that skepticism."

On the campaign trail, she was insulted and her patriotism was questioned.

"I write about those, you know, those nasty times where people, you know, called me Barack's 'baby mama,' you know? Accused me of not loving my country. ... Told me I was angry," she said. And, I was, like, 'This isn't me. Wait, wait, people. This isn't who I am.'"

Obama told Roberts that the criticism she endured during her husband's campaign hurt.

"I don't think we do each other a service by pretending like hurtful things don't hurt," she told Roberts.

"And, that's what I've come to. ... I need to own that hurt. I need to talk about it. I need to put it out there for myself so that I can heal from it. But at the time, oh gosh, you know? I wasn't gonna allow myself to feel victimized from it because there was no time to hurt in that role."

In her memoir, "Becoming," which is out on Tuesday, Michelle Obama writes that she will "never forgive" President Donald Trump for challenging the legitimacy of her husband's birth certificate.

In 2011, Donald Trump and other so-called "birthers" were questioning whether Barack Obama was a U.S. citizen. In her memoir, Michelle Obama described their actions as "crazy and mean-spirited. ... Its underlying bigotry and xenophobia hardly concealed. But it was also dangerous, deliberately meant to stir up the wingnuts and kooks."

In audio from the book obtained exclusively by ABC News, Michelle Obama wonders: "What if someone with an unstable mind loaded a gun and drove to Washington? What if that person went looking for our girls? Donald Trump, with his loud and reckless innuendos, was putting my family’s safety at risk. And for this, I’d never forgive him."

President Trump responded Friday to Michelle Obama's comments about him in her book, pointing the finger at former President Barack Obama.

"She got paid a lot of money to write a book and they always expect a little controversy," Trump told reporters. "I'll give you a little controversy back, I'll never forgive [President Barack Obama] for what he did to our U.S. military. It was depleted, and I had to fix it."

"What he did to our military made this country very unsafe for you and you and you," Trump said.

Michelle Obama also writes about her reaction to Trump being elected president and her thoughts while she was watching his inauguration, writing, “I will always wonder about what led so many women, in particular, to reject an exceptionally qualified female candidate and instead choose a misogynist as their president.”

"It's amazing to me that we still have to tell people about the importance of voting," Obama told Roberts.