Oscar winner Charlize Theron, who gained 30 pounds to play a serial killer in the 2003 drama Monster, recently quit smoking and couldn’t be happier.

“I was highly addicted,” Theron, 36, says in the December 2011 issue of Vogue. “I thought, I don’t smoke like normal people. I smoke to die.”

The 5′ 9½” South African stunner reportedly smoked up to three packs of cigarettes a day, and is rumored to have used hypnotherapy to help her kick the habit.

Amazingly, Theron looks leaner and fitter than ever, apparently having managed to avoid the weight gain typically associated with smoking cessation.

Charlize, a former dancer, also began embracing a healthier lifestyle after overcoming her nicotine habit, including doing Pilates and yoga.

Theron, who split from actor boyfriend Stuart Townsend after 9 years together, is happily single for the first time in a while.

“I’ve never been single,” says Charlize. “This is the first time in my life. From the time I was 19, I’ve been in relationships, literally gone from one to the other within a month.”

Theron, who appears next in the drama Young Adult, is basking in her newfound single status for now.

“It’s been good for me,” she says. “I’m a creature who’s really found her comfort zone in relationships.

“It’s been nice to rediscover myself. I had to make a real conscious effort to do it—it’s hard. It’s much easier to lose yourself in flowers and cigarettes and coffee with somebody else.”