A squeaky-clean member of the Jonas Brothers no more, Nick Jonas is embracing his solo career and beefed-up image makeover.

"It's a big transition," Jonas said in a recent interview. "I am stepping into what is really like starting over and that's exhilarating, but also really frightening."

Fans may remember the former Disney star as the youngest brother in the successful pop trio that split last October. Now 22, Jonas is launching his next chapter, which includes a self-titled album, out Nov. 11, and the much talked-about, Marky Mark-inspired photo shoot for Flaunt magazine.

"It was pretty interesting to watch the reaction," Jonas said of the revealing photos. "I feel like the best way to approach it is to not take it too seriously."

The spread recreated Mark Wahlberg's 1990s ad campaign for Calvin Klein — complete with crotch grabbing. Jonas welcomed the attention from the images that went viral last month.

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"There is the argument that it could eclipse the other projects, but the week that shot came out, the single went up 100 percent in sales," he said of "Jealous," which jumped to No. 27 on Billboard's Hot 100 chart last week.

Jonas' recent physical transformation is also making headlines. Managing his Type 1 diabetes has always required a healthy lifestyle, but he took on an intense training regime after being cast as a mixed martial arts competitor on DirecTV's "Kingdom," which airs Wednesday at 9 p.m. EST on Audience Network.

Jonas packed on 15 pounds of muscle in two months through twice-daily cardio and strength training sessions followed by six to seven hours of MMA training.

"I'm the kind of person that loves a challenge and I had reached a point right before it when I was just ready," he said. "My grandfather, who I was really close to, passed. And right after that everything fell into line. I feel like he was orchestrating all of it, which is really kind of special."

Jonas' girlfriend, Olivia Culpo, who was Miss Universe 2012, also helped keep him motivated through the grueling workouts, despite some heckling from his famous family.

"My brothers were kind of making fun of me a little bit as I was doing it because I was getting really big," he said. "But my girlfriend is also really into fitness so it's nice to have a teammate, a partner, who is down to do it with me and kind of explore that with me."

He said his buff new image is just a piece of his career reboot. Jonas' new music is also a departure from his purity ring, boy band days: Though he has released albums apart from his brothers in the past, on his new album he's singing mostly of love and lust. Jonas channeled soul and R&B flair from some of his favorite artists like Stevie Wonder, Prince, Lionel Richie and the Bee Gees.

"The goal this time around is to surprise people in all elements with the music and with my voice specifically, but also with my transparency in the lyrics and the way I'm trying to carry myself," he said. "(To) just be me and not being afraid to say or do anything outside of the realm of what I should be doing."