Racy scenes in the final installment of Twilight had Kristen Stewart and real-life beau Robert Pattinson scrambling to keep fit and toned at the last minute.

"I did On The Road right before Breaking Dawn and I definitely did hang out a little bit," Stewart shared.

"Then when I was doing prep for Breaking Dawn I suddenly realized, 'This is so not On The Road. People definitely want to see you looking trim." the actress added.

Pattinson seconded their hard work, telling MTV he went without candy and beer for a while in an attempt to be more health-conscious.

"I went kind of nuts," the British heartthrob admitted.

"Me and Kristen went nuts working out, because we hadn't worked out for any of [the previous films]." the movie vampire claimed.

The Twilight beauty also revealed their co-stars enjoyed seeing the pair sweat it out.

"Usually we're all making fun of Taylor Lautner for working out so often. And then suddenly me and Rob were like, 'Shit' and running around the block while Taylor laughed at us." Stewart shared.

The much-anticipated final two installments of the hit vampire franchise feature decidedly more adult themes than the previous three films.

In the December issue of Glamour magazine, the twenty-one year old admitted the steamy scenes initially caught her off guard, calling it "surreal".

"It was so weird, it didn't even feel like we were doing a Twilight film. I was like, 'Bella! What are you doing? Wow! What is happening here?!'" Stewart explained to Glamour.

The scenes between Stewart and Pattinson were deemed too explicit that it was originally rated R. Considering many Twilight fans are teenagers, producers decided to re-cut the film to avoid the R rating.

Breaking Dawn Part 1 director Bill Condon offers technical insight on the pivotal scene.

"I hate to be clinical, but guidelines on thrusting intercourse," Condon told Celebuzz. "Anything that suggested that - not to make people too excited it was never explicit - but I think any movement that suggests that is what they object to. I suspect that because of the popularity of Twilight we had an even bigger focus." added the director.