The cover of the new issue of Women's Health magazine promises that inside, you'll hear Carrie Underwood's Slim-Down Tricks. So, of course, you have to buy it. But while I was hoping for some easy magic bullet, all I really got was Tabata. And that is not easy.

Underwood's latest discovery is a kind of high-intensity (meaning practically impossible) interval training. Her system is to do one exercise over and over to target one part of her body.

"When I do pushups, I'm dropping to my knees halfway through," she told the magazine. "When I do abs, it hurts. But I like it. It makes me work."

And she always says she's not afraid to admit she wasn't always at such a physical peak.

"I'm not embarrassed [by old pictures] because there was a lot I didn't know," she said.

One fitness routine Underwood always skips? The high-end designer workout clothes.

"I've had the same shorts for years, and I'll wear them until I can't wear them anymore," she said. "People who dress up for the gym? I don't like them."

When she's not trying to do all those workouts on the road, Underwood likes to go do hot yoga in Nashville. She had to tell the instructor not to push her too hard, though, saying, "This is my stretchy time. I'm here to relax and stretch out all the stuff that I've done to myself over the week."

As for the diet part of her Slim-Down Tricks, Underwood has always talked openly and honestly about becoming a vegetarian, keeping a food diary and cooking on her bus. But in this story, she gives a few more specifics on her obviously successful diet. She always has boxes of Dr. McDougall's Pad Thai and Lentil Pilaf, Ezekiel bread ("It's not like white sandwich bread. It has grains like barley. Once you get used to it, you can't go back") and Better'n Peanut Butter. Although Underwood says she isn't a sweets person, she does likes to spread this super-healthy PB on apples.