WENN 1 / 9

It's not easy being a Vogue cover girl! While taking to Jay Leno on Friday, Katy Perry admitted that the July issue photo spread -- shot by famed photographer Annie Leibovitz -- required intense preparation.

PHOTOS: Katy and Russell Brand -- the way they were

"I did a lot of my own prepping," the "Wide Awake" singer, 28, said of the cover that was shot on a farm in Upstate New York. "I kind of went on a cleanse, I did a lot of stuff like vitamins and supplements, I changed my coffee to green tea, I didn't drink alcohol for three months."

"I was really in the zone, I just wanted to be glowing for that cover," she continued.

Indeed, in May, John Mayer's current girl showed off various supplements she was taking in a Twitter picture. "I'm all the about that supplement vitamin LYFE," she wrote with the pic.

PHOTOS: When exes attack

Despite the regimen, Perry seemed pleased with the end result -- sharing how "amazing" it was to work with Leibovitz. "She's incredible," she said. "It was really fantastic working with her. She [has] such a great vibe, she's got no ego which is fantastic, and she really let's me be creative as well."

Perry, who voices Smurfette in the upcoming July 31 "Smurfs 2" movie, also opened up about the vibe of her upcoming album, which she said will debut "soon."

PHOTOS: John Mayer's famous exes

"I've had a lot of time to reflect, and I think that it will continually be what I always do -- connecting to my core and trying to bring an honest message that people can relate to," she said.


Katy Perry incites Twitter feud with 17-year-old rapper

Julianne Hough, Katy Perry, and more celebs who had breakup makeovers

John Mayer dedicates song to Katy Perry, thanks her for being 'so patient'