Charlize Theron almost passed out on the first day of filming new movie North Country because she had to face her worst fear and speak publicly at a mining union meeting.

The actress plays a sexually harassed miner in the movie, which is based on a real-life story, and actually had to stand up in front of a room full of extras and real miners for a harrowing scene on day one.

She recalls, "I get this really strange sensation (when public speaking) where everything goes black, and I see white spots, and I break out in hives. It's probably the most frightening thing you can make me do.

"It was my first day of shooting, and, literally, I couldn't breathe. I couldn't talk. I thought I was going to faint. I didn't know what was happening."