Maggie Siff on Those Dominatrix Sex Scenes in 'Billions' : 'I Have to Laugh'

What’s the key to acting your way through steamy BDSM scenes? “You have to bring an incredible sense of humor to get yourself through it,” says Billions actress Maggie Siff, laughing. Siff plays a powerful psychiatrist who is also a dominatrix on the Showtime show, and shares a slew of steamy, sexually-charged scenes with co-star Paul Giamatti, who plays her husband.

“When I first read the pilot and read that she was his dominatrix, the first thing that occurred to me was they must have some kind of healthy marriage to make room for that,” Siff tells PEOPLE, adding that she and Giamatti relied on their senses of humor to work through any initial embarrassment. “We just kind of laughed our way through it. We were both deeply embarrassed in different ways, but also really interested in telling the story and doing it well. We had a lot of laughter on set and it’s what’s necessary to get you through.”

The New York-born actress, who’s appeared on Sons of Anarchy and Mad Men, discovered her passion for acting during a high school production of A Midsummer Night’s Dream and is grateful she’s been able to play so many smart, strong women.

“As I’ve gotten older I’ve grown into roles that suit me the best,” she says.

When Siff isn’t playing successful, strong women, she is relishing her role as a mom.

“I have a 2-year-old. When I’m not working I’m with her, I want to spend as much time with her as I possibly can before this delicious babyhood is gone and it’s going fast,” she says. “I feel very lucky because I get to go to work and be this glamorous strong woman who is incredibly autonomous and doing her thing, and then I come home, get back in my sweatpants and get on the floor with my child and I get to step out of it sometimes which is nice and keeps me sane. But I love being a mom so much.”

Billions airs Sundays on Showtime.