"I would say that was a challenging one for me. I just had to do it. We rolled the cameras and I just had to bite the bullet," the 44-year-old actress told reporters in New York Saturday.
"It was a little uncomfortable at first, but then you get into it. Doing the rehearsals alone with [the choreographer] and then all of a sudden you're on the set and there's three cameras and a bunch of crew. Yeah, it was a little intimidating at first."
Told she looked amazing in the movie and asked for advice on how others might follow her lead, Aniston replied: "No secrets and it's not a few tips.
"I don't think you have time for that answer. It was an amazing choreographer and wonderful trainer and a beautiful cinematographer. All that good stuff. And I worked out a lot."
So, did she avoid eating carbs during the shoot to maintain her physique?
"Oh, no, no, no. No food. There were a lot of salads. Celery sticks. Cucumbers. Ice chips. They did let me eat ice chips. Water was good. You could eat normally. But no carbs," she said.
In the film, Jason Sudeikis plays David, a small-time Colorado drug dealer whose pot stash is stolen, forcing him to promise his supplier he will transport a load of marijuana across the Mexican border into the United States to repay him for what he lost. David's boss, played by Ed Helms, even offers David a hefty bonus as part of the deal.
Figuring a squeaky-clean-looking family in a recreational vehicle will draw less attention from authorities than a single man traveling alone, David enlists three people he barely knows to pretend to be his wife and kids.
Although David's stripper neighbor Rose; Kenny, a sweet, but clueless teen who lives in their apartment building; and Casey, a self-absorbed, homeless girl, initially agree to the road trip because they are lonely and cash-strapped, the quartet of unlikely drug smugglers bond along the way, developing real affection for each other.
Aniston plays Rose, while Will Poulter plays Kenny and Emma Roberts plays Casey in "We're the Millers," which opens in theaters nationwide Aug. 7.