Credit: Courtesy of Self

When it comes to kids, four is just enough for Carrie Underwood, thank you very much.

In the January issue of Self magazine, the country star gets pretty specific about her goals for starting a family. "Someday I'd like to start a family," Underwood, 26, says. "Not a big one, but not a small one either."

The middle ground between "big" and "small"? "Two kids is good," she explains. "Three is fine. Four? Somebody's getting something done, because we ain't having five!"

The singer has been dating Canadian hockey player Mike Fisher, 29, for just over a year.

She also shares some of her fitness secrets. Her personal trainer: Jillian Michael! "I have Exercise TV on cable," Underwood clarifies. "Jillian Michael's videos will kick your butt."

Another exercise regime is also a stress-reliever: "If I'm ticked off, I'll get a punching bag and beat the crap out of it."

And she does check out published photos of herself. "I love it when I feel good about myself," she admits. "I'll look at a photo and think, 'My arms look great!' -- and then I go work out on my arms. Once you're enjoying things about your body, you realize how much you want to keep them that way or make them better."