How did Mike "The Situation" Sorrentino get his six-pack?

Certainly not from steroid enhancements, Sorrentino tells Nightline's Chris Connelly.

"Oh never, never, never," Sorrentino tells Connelly when asked on Monday's episode if he's ever taken the drugs. "The steroid look is definitely a bulkier look. I have a more thin, lean look. And I don't judge. If somebody's going to take steroids, that's their prerogative and their body." (Watch a clip above)

So how does the 27-year-old Dancing With the Stars competitor keep his body in check?

Lots and lots of cha-chas with pro partner Karina Smirnoff -- and a little help from mom and dad.

"I'm dancing 6-8 hours a day, but I guess I'm genetically gifted," Sorrentino says.

Nightline airs Oct. 11 at 11:35 p.m. (EST) on ABC.