The actress explained that she gave up her social life when she landed the role as the iconic vampire slayer as a teenager.
"I was 18 years old when I started Buffy, and work was my everything," Gellar recalled to Self. "Back then, no actor had worse hours than I did."
Since Buffy the Vampire Slayer ended in 2003, Gellar and husband Freddie Prinze Jr have welcomed a daughter named Charlotte Grace.
The actress returned to television in The CW thriller Ringer earlier this year, but says she insisted on a more flexible work schedule.
Gellar said: "Now I don't work on weekends anymore. Everybody knows you can't sway me on that point, so nobody even tries. Plus, my perspective on work has changed: Work doesn't define who I am.
"I love what I do, but I don't feel a burning pressure anymore. And because I'm working for fun, I get to enjoy it. I'd watch Ringer if I wasn't on it! Of course, it's not as much fun when you know what's going to happen. It takes some of the excitement away."
Gellar previously commented that she doesn't own scales because she isn't concerned about her weight.
Ringer, which has received a full season order, continues with new episode 'That's What You Get for Trying to Kill Me' on Tuesday, November 29 at 9/8c on The CW.
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