Britney Spears Says 'Till The World Ends' Has 'Good Energy'

'If it puts me in a good mood, it clicks for me,' singer tells Ryan Seacrest of Ke$ha-penned track.

Britney Spears got her fans amped up for her forthcoming album, Femme Fatale, when she released its second single, "Till the World Ends," on Thursday. The chugging, Ke$ha-penned club banger is all about getting your dance on. And when Spears stopped by Ryan Seacrest's radio show on Friday (March 4), she admitted that the song just felt right for her as soon as she heard it.

" 'Till the World Ends' is fun! It's fun. I like it. It's good energy," she said of the track, which was produced by Dr. Luke, Max Martin and Billboard. "I'm a vibe person, and I think I love good-mood songs, and if it puts me in a good mood, it clicks for me."

As for the album, which already spawned a chart-topping single, "Hold It Against Me," she teased, "I think it's my best work yet. I listened to it on the way over here. It's definitely something you want to work out to. ... And I'm a dancer, so it's definitely something I can work with."

"Oh my God! is amazing," Spears said of the producer, who teased the track "The Big Fat Bass" recently. "He's so much fun and he's funny and he's a charm. His music is so much fun. When they told me I was going to be working with him, I couldn't wait. If it gets you going, you get excited, and he has that type of energy."

In addition to talking about the album, Spears also shared plans for a summer tour. And she talked about how she's keeping in shape these days as she amps up to promote the album, which drops March 29. "I have a trainer. [I go] on the treadmill for 30 minutes and we do a lot of cardio, running," she explained. "He kicks my butt. You pay to hate your trainer!"

It seems that the workout regimen has also had an effect on her beau, talent agent Jason Trawick, who, according to Seacrest, was "pudgy" before he hooked up with the pop star. "He wasn't pudgy," she laughed. "He wasn't pudgy. He is definitely ripped. He just got on this health kick. I guess he's on a health kick. He eats what he wants."