In high school, says the Checotah, Okla., native, she suffered panic attacks, Underwood tells WebMD the Magazine. Particularly problematic was Christmas shopping, which, she says, "seemed to be my worst nightmare."
The issue appeared to be the close proximity to others. "I'm a big personal space person. You know, if you go to the restroom, you use the stall that's not near anybody. Or if you're in the gym, you go to the treadmill where there's space in between you. And it seemed like in crowded situations like that, people would just completely violate your personal space," she says.
"So, whenever I'd be in stores and there would be people touching me and kids running around, I couldn't take it and I'd have to leave."
Though she has put the problem behind her, Underwood also says that having to adjust to dealing with crowds once she hit it big on American Idol in 2005 required some effort.
Fans, she says, "feel like they know you and they love you and that's wonderful – they're excited to meet you," she says. "It just took me a minute to be able to figure that out and to be able to allow people into my space."
Keeping FitUnderwood, 27, also now maintains a healthy mind and body – not an always easy task, given her constant touring schedule and its pitfalls of sleep deprivation, fast food (which she avoids) and even germy hotels – which she has her dog Ace sniff out.
According to WebMD, Underwood has five steps to staying in shape. They are:
1. Work out. "Cardio makes me feel good, it makes me happy. It really makes a noticeable difference."
2. Eat healthy. "I'm not a huge pill taker, because I feel like our bodies are designed to take what we need out of food. So I don't want to make my body deficient and make it depend on what I take. I'd rather eat and drink things that are good for me."
3. Keep washing. "I'd rather take preventive measures than get sick and try to battle things off. So I do wash my hands quite a bit."
4. Get some rest. "I enjoy naps but only on days off, because I can take, like, a three-hour one. I'll take a nap if it's just a total rainy day off and there's nothing you can do anyway."
5. Give back. "People think, 'I don't have time to volunteer,' but there are little things you can do to make the world better and raise awareness, whatever your passion is. Like if you go to facebook.com/Pedigree, you can become a fan, and they'll donate a bowl of food to a shelter dog. That's a free meal, and it took 30 seconds of your life."