Fitness 'addict' Demi Lovato stays buff (and sane) by spending four hours a day in the gym

If you're going to go on tour with Nick Jonas, possibly music's buffest star, you'd better look your best.

But for Demi Lovato, the hottest Jonas brother's recent tour mate, her workout goals aren't necessarily inspired by aesthetics. She trains like a madwoman for her mental health.

Apparently, one must be in tip-top mental condition to publicly feud with the likes of Taylor Swift and Mariah Carey.

"This is her safe haven," Jay Glazer - who manages the LA gym Unbreakable where Demi, 24, Nick, 24, and his brother Joe Jonas, 27, train – told People magazine.

"Demi will be here for four hours a day. It's her one place where she doesn't have to be a pop star. She's talked a lot about her addictions, and this has become her healthy addiction. She lights up when she comes in here."

Clearly Demi is a glutton for punishment. She begins each session with 90 minutes of mixed martial arts, which include boxing, Muay Thai, ground fighting and/or Brazilian jujitsu.

Then she focuses on toning up with a "performance workout".

"It's very intense," Glazer says. "It's three different exercises three times through with no rest. She'll do a push, a pull and lower body move, so let's say a chest push, a pull for your back, and then some sort of squat, but something low-impact that won't bulk her. At the end we'll do abs."

We're sweating just writing about it.

Next up: 30 minutes of recovery, and it's not just about doing a few stretches and calling it a workout.

Demi's recovery includes I.V. therapy, cryotheraphy and medical laser therapy and massaging recovery sleeves. Um, we'll stick to our easy stretches, thank you.

But according to Jay, Demi never skips a beat…or a workout.

"She goes through the plan perfectly," says Glazer. "She's never been late, she shows up, she helps everybody. She's incredible."