Ann Romney revealed for the first time she had a health "scare" during the days leading up to the Super Tuesday primary contests, indicating that her battle with multiple sclerosis could limit the time she spends on the trail with her husband.

"There have been some days, like the day before Super Tuesday, I was quite fatigued and I knew I couldn't quit. I didn't tell anybody I was tired," Romney told "Entertainment Tonight's" Nancy O'Dell, when asked how her multiple sclerosis diagnosis affects her time on the trail.

"I just kept going, I kept going. I had a little bit of a scare," Romney said in clips released before the full interview airs Thursday.

O'Dell asked Romney to describe the health scare.

"What happens with me is that I start to almost lose my words. I almost can't think. I can't get my words out. I start to stumble a little bit and so those things were happening and I thought, 'Uh oh, big trouble,'" Romney said.

She was diagnosed with MS in 1998 and was so sick at one point she thought she would be confined to a wheelchair. It's a story she often tells at campaign events, always adding how her husband stood by her through the low points by telling her he would "eat cereal" for the rest of his life if it meant she couldn't cook or do the other household duties she usually took care of.

She has had an incredible recovery. Romney has said riding horses helps her stay healthy and keep the MS almost symptom-free aside from fatigue. She has said in past interviews that she watches closely how much energy she exerts and time she spends campaigning.

After Super Tuesday, Romney took some time off the trail, staying in Boston for a few days before going to Florida with her husband. She often takes days off the trail, spending time at her home outside of Boston and in La Jolla, Calif., where the Romneys have another home. She even took 10 days off the trail after the March 20 Illinois primary, spending it in California.

This week, she introduced her husband at his event in New Hampshire intended to marked the start of his general election campaign, and she campaigned solo, as well, speaking at a Connecticut GOP dinner.

In the Entertainment Tonight interview, O'Dell asked Romney what she hates the most about being in the public eye.

"I do think that people are highly critical, or maybe the judgment that they might lay on you is completely off base, or things like that," Romney answered. "But that just goes with the territory."

O'Dell asked her about comments by Democratic strategist Hillary Rosen, who said Ann Romney had "never worked a day in her life."

Romney laughed and then answered, "It was wonderful to see the [positive] reaction because everyone knows that doing the job of raising kids is one of the hardest jobs we have.

"It's also a job that never ends, and I have to tell you my children are all grown now [and] it still never ends," Romney said. "It was my choice, it was a career choice I made, and I want people to recognize that it was a choice and it was a choice that I love and I cherished. Listen, it was hard. They were really rowdy."

The full interview will air on "Entertainment Tonight" Thursday evening.

ABC News' Emily Friedman contributed to this report.