Kristen Stewart used to make herself ill if she wasn't in control.
The 25-year-old actress struggled to cope with her "intense" early success and was "constantly anxious" worrying about what could happen.
She said: "Between ages 15 and 20, it was really intense. I was constantly anxious. I was kind of a control freak. If I didn't know how something was going to turn out, I would make myself ill, or just be locked up or inhibited in a way that was really debilitating."
Kristen - who causes a scandal in 2012 when it emerged she had cheated on then-boyfriend Robert Pattinson with her 'Snow White and the Huntsman' director Robert Sanders - admitted she has become more "feral" and less concerned about her image in recent years.
She said: "Lately, I've been doing less of the 'I'm sooooo sorry.' And more of the 'No. F**k. Jesus.'...
"Speaking very candidly, it was a really traumatic period in my early 20s that kick-started something in me that was a bit more feral."
And the 'Twilight Saga' actress - who is rumoured to be dating her assistant Alicia Cargile - is "proud" she is learning to be a "smarter and calmer" person.
Speaking to America's Marie Claire magazine: "I'm really proud that I am able to move forward and not fall into every mental crater. That's a new thing for me. Age has made me smarter and calmer. And it is f***ing awesome."