“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.