09/06/2007 at 03:00 PM EDT
As she prepares for her debut this month on Showtime's Weeds
, Mary-Kate Olsen
says she's in good health.
"Mentally, physically, I feel pretty on top of my game right now," she tells EW.com
. "Talk to me next week, I don't know. Today, I feel good."
The actress, who turned 21 in June
– and who, in 2004, was treated for an eating disorder
at Cirque Lodge in Utah – admits that she makes "conscious decisions every day of my life" to avoid being photographed by paparazzi.
"I would love to be able to swim in the ocean in Malibu," she says. "But that is asking for a bikini shot. That's inviting something that I don't want to happen. I don't need to be on a 'Who's Skinny, Who's Fat, Who's Looking Healthy, Who's Not Eating?' list."
Olsen reportedly also avoids photographers by steering clear of certain celebrity-friendly stores, keeping her small frame close to her beefy bodyguards and having friends over for dinner instead of meeting them at restaurants.
Still, when you're one half of the world's most famous set of twins, cunning photogs are bound to find you. Her solution? "I cover my face so they don't get a picture," Olsen says, which unintentionally makes her "the mean person who doesn't smile" in photos.
As the first of her 10 TV episodes of the suburban drug-dealing drama approaches on Sept. 17 (Olsen plays Tara, a Christian girl who is new to the neighborhood where the drug-dealing main character lives), she's excited to prove herself as an actress: "To say that I got to work with those people – with Mary-Louise Parker! – is a great thing."
It's a new direction for the former child star, who tells EW
that the work she did growing up with her sister Ashley "wasn't about acting" but rather "about pleasing other people and making kids smile."
And although a serious Hollywood career is now before her after more than two decades in the spotlight (she recently wrapped The Wackness
with Ben Kingsley), Olsen admits it hasn't always been easy: "There's definitely been times in my life when I just turned to people and said, 'I'm done, this is too much for me, this is too overwhelming.' "