"I think as you get older, you really get to the point where you just don't care anymore what people think," she says. "There's a certain freedom that comes with that, [which] you really don't have when you're young. With age comes a lot of wisdom and I'm happier now than I have ever been, so it's good."
Smith says she embraces everything about herself and feels comfortable telling others, "This is me, this is my skin, this is my face, this is my body, love it or leave it."
"I've gotten older, I've gotten more acceptance from myself and I think that releases a lot of stress," she continues. "I take really good care of my body."
Smith also credits her toned physique to her mother, Adrienne Banfield-Jones, who recently tied the knot to her longtime boyfriend earlier this month.
"My mother is 63 and is still looking fine," she quips. "I'm hoping she passed that gene to me, we'll see."
The Gotham actress also shares her secret to parenting and family life.
"You know, it really is putting one foot in front of the other. I wish I had a formula," she explains. "I think it's just knowing my priority. No matter what I am doing, my family is always my priority and I think that is what made it easy."
"In the earlier stages of my family and career… I wasn't quite sure all the time what the priority was and what the priority should be," she adds. "Switched back and forth and then it just got to the point where my family is a priority. Once I had that main priority as my core, everything else falls in place where it needs to be."
Smith will reprise her role as Fish Mooney in season three of Gotham, which airs on Mondays at 8 p.m. ET on Fox. For more on her villainous role, watch the video below.