Swank's new film "Freedom Writers," which is based on a true story and comes out Friday, features her as a first-time teacher who inspires inner city students to change their lives, "ExtraTV" reported Wednesday.
"It's amazing how that person can make a difference, even in one person's life," said Swank.
As for her inspiration, the actress told "Extra": "It was my mom. My mom was really the person who believed in me and told me I can do anything I want in life."
The actress also admitted that she carries around a fear that someday her success will disappear.
"Certainly there's that fear, is this going to be my last movie? Am I going to be found out and, 'You! How'd you get in?'" she said. "There's always that, yeah."
Notable deaths of 2014 [PHOTOS]