Kelly Clarkson: ‘I Can Whup A**’ (VIDEO)

Kelly Clarkson was an interesting choice for Self’s September cover.

Kelly has famously struggled with her weight — not too unlike Jessica Simpson — and has put on significant pounds in her career. In fact, Kelly hasn’t really looked svelte in years.

Lately, however, she has started toning up with CrossFit, a strength training and cardio program used by police academies and military special operations.

“I love it! It’s like boot camp,” she says. “It makes me feel like GI Jane. It’s very empowering. I feel like I can whup a–! And in my shows, everybody has noticed. They’re like, ‘Dude, you have 100 percent more energy!’

Check out her behind-the-scenes video shoot below: