The usually surly Kristen Stewart was smiley and surprisingly open about her life at the 2014 Sundance Film Festival ... well, sort of.

The onetime 'Twilight' star was promoting her new movie, 'Camp X-Ray,' in which she plays a soldier named Young Cole who's guard at Guantanamo Bay. And it wasn't an easy job!

"I was so nervous when I first started working and preparing because I didn't think that people would believe me or think that I looked tough in a uniform," Stewart revealed to MTV News. "That I could do that job, that I could wrangle detainees that are massive and scary."

Hey, she kicked a lot of butt in 'Snow White and the Huntsman,' right?

The role also inspired a major change in the actress' life: a new puppy! "I have a pup, yeah," she smiled. "I actually got on her on 'Camp X-Ray' and named her my character name, which is so embarrassing," she giggled. "But it's so cute. Young Cole! She's a mutt. We found her on a frisbee golf course, and she was small and scared."

Just don't ask her to delve even skin deep about her personal life. She refused to discuss her new tattoos, explaining that keeping her life as private as possible was her goal. "That's the plan, yeah."

Good plan, K-Stew. On that note, you may not want to hook up with married men outdoors ever again.