Donna Mills does 100 sit-ups a day, plays tennis five times a week at 85 but won't quit Doritos

Donna Mills is keeping fans on their toes at 85, from launching an OnlyFans account to revealing the intense fitness routine she credits with keeping her active.

The former ballerina, best known for playing the scheming Abby Cunningham on "Knots Landing," revealed to Fox News Digital the demanding fitness routine she credits with keeping her moving — including 100 sit-ups, 50 leg lifts, up to an hour on the bike and, sometimes, tennis five days a week.

And while Mills has long been disciplined about her health — including cutting out sugar — there is one indulgence she refuses to completely give up. 'KNOTS LANDING' STAR DONNA MILLS SAYS REFUSING TO POSE NUDE COST HER PLAYBOY COVER "I’m a Doritos addict," Mills confessed.

The actress revealed that nacho cheese is her flavor of choice, showing that even her disciplined wellness routine leaves room for a guilty pleasure.

"I mean, it’s not good for you.

It’s not.

You know, I know I shouldn’t do it," Mills admitted.

WATCH: 'Knots Landing' star Donna Mills swears by this daily routine at 85 Still, she said the popular snack has followed her throughout her decades-long career.

"Different sets that I’ve been on… for some reason, they know — they always got a bag of Doritos in the trailer for me… it’s really funny.

But I’ve never lost that.

I don’t eat them as much as I used to.

But they’re still a treat." When it comes to exercise, Mills' routine is considerably more demanding.

"I started out as a dancer, so a ballerina.

I mean, I was on pointe, the whole thing," she said. 'KNOTS LANDING' STAR DONNA MILLS ISSUES URGENT WARNING ABOUT AGING Mills said her early training instilled a work ethic that has stuck with her throughout her life.