Mila Kunis Mila Kunis

Filming a love scene with Natalie Portman in the upcoming film Black Swan wasn't exactly an easy day at work for Mila Kunis.

VIDEO: Natalie Portman and Mila Kunis share a kiss in Black Swan

"Any time you do any intimate scene on film, it's going to be a little uncomfortable, whether it's the same sex or the opposite sex," Kunis said at a news conference

to promote the film, a psychological thriller about competing ballerinas played by Kunis and Portman.The former That '70s Show star said the Black Swan scene was made easier because she and Portman weren't complete strangers. "The great thing about this is that Natalie and I were actually lucky enough to be friends prior to production, which made it all a lot easier," Kunis said. "We didn't really discuss it very much. We just kind of did it. It made sense for the character. It wasn't put in for shock value. It wasn't something that we needed to justify in our heads, as to why we were doing it."

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Kunis, who began acting at age 9, also recently revealed that she nearly gave up acting when That '70s Show ended. "I was like, 'All right, this has been a god run, but I'm done,'" Kunis told Nylon magazine. "I wanted to rethink my life for a minute because I didn't think acting could be a career. ... The whole thing is based so much on opinion and nobody is wrong. That person can think I'm great, that person can think I suck, and they're both right. I was like, 'Can I really do this for the rest of my life?'

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"What a lot of people don't realize is that you make more money in TV than you will in film," Kunis said. "It's a very steady salary. An obscene amount of money gets given to you for, like... what? So I was 20, and I looked at my bank account and realized that I was secure for the rest of my life. I was like, 'I'm okay. I can go do other things now.'"

Black Swan — which is already creating Oscar buzz for director Darren Aronofsky, Portman and Kunis — hits theaters on Dec. 3.