Taylor Swift talks weight, virginity, and her fascination with fairy tales in an in depth interview in the April issue of Allure.

Oh, and by the way, if you break her heart, she guarantees you’ll become the subject of a charttopping single.

“I’m the kind of person who needs everything to be justified and needs all of her time to be worth the energy,” Taylor tells the mag. “So, let’s say I date a guy who really does nothing but damage me. And you’ve spent time, you’ve spent effort, and you’ve put everything into trying to make that work. And it didn’t. So you write a song about it. It was worth everything, if you write a song about it.”

Taylor Swift on Weight: “Basically, if I’m indulging too much and not exercising enough, I can feel that,” she says. “I can feel a change before I see it. For me, working out is not so I can stay skinny. It’s so that I can keep up my endurance so I’m not panting on stage. Heavy breathing is the worst when you’re in concert. You don’t want to see that, if you’re going to see a show.”

Taylor on Keeping Mum on Her V-Card: “It’s fine to talk about love publicly. But I think when you talk about virginity and sex publicly, people just automatically picture you naked. And as much as I can prevent people picturing me naked, I’m going to.”

Taylor Talks Fairy Tales: “I have always been fascinated with fairy tales… and the idea that Prince Charming is just one castle away. And you’re gonna run across a field and meet each other in the middle, and have an amazing, perfect movie kiss. And it’s all gonna be happily ever after.”

For more photos of Taylor, or to read her profile, “The Story Teller,” check out the April issue of Allure, on newsstands March 24.