"It just grounded me, and made me feel good about myself for something that had nothing to do with glamour or fame," McKellar said. "And I found out I was pretty good at it."
She wasn't just good at it. McKellar was a math whiz. She helped solve a physics problem that will now forever bear her name: The Chayes-McKellar-Winn Theorem.
"Now I'm in the Journal of Physics forever and ever," said McKellar.
But even with her success in math, McKellar's love for performing was always part of the equation. So she ultimately decided against a career in academia and returned to acting in movies and television shows like "The West Wing."
And for the past five months, she's been in Dallas, writing and acting in a new mystery series for the Lifetime Movie Channel called "Inspector Mom."
"It's a combination of those two sides of the brain," McKellar said. "You need to know how people respond to situations emotionally and how the clues have to be divulged and at what point. All of that is very much problem solving. It's a puzzle. It's a math problem."
McKellar has a Web site where she helps solve problems sent to her by fans, and she's writing a book geared toward getting girls interested in math. As for living in two different worlds, McKellar enjoys the opportunity to pursue both of her passions.
"It's a real challenge to be able to reinvent yourself, to find that you're not just resting on your laurels but you're actually still a person who's alive and growing and doing things that matter," she said.