Danica McKellar is in the best shape of her life at 39, thanks to a low-carb gluten-free diet, yoga workouts, and lots of dancing.
"I don't eat gluten, I don't eat dairy, I don't eat sugar," McKellar told People. "And the only thing I drink is water. I eat really, really clean. I'm very strict."
Danica, who starred on the hit TV series "The Wonder Years" from 1988 to 1993, said she doesn't deprive herself, but makes a point to fill up on nutrient-dense, whole foods.
The super-toned McKellar, who's competing on season 18 of "Dancing With the Stars," said her usual workouts are low-impact and center around yoga. "I do yoga, I actually have a yoga DVD called 'Daily Dose of Dharma,' " she said.
Lately, Danica has been working out up to seven hours a day for "Dancing With the Stars" with partner Valentin Chmerkovskiy. She said the grueling dance training is fun but exhausting.
"I've been taking ice baths every single night," she said. "Hot shower, ice bath – I've been going back and forth between the two. It's very unpleasant, but worth it."
After McKellar hit it big as a child star, she pursued a mathematics degree at UCLA and graduated with honors. Danica then went on to write three New York Times-bestselling math books for children, including Girls Get Curves: Geometry Takes Shape.
For now, the divorced mom of a three-year-old boy is enjoying competing on "DWTS." She dismissed rumors that she and fellow contestant Candace Cameron Bure are bitter rivals. "We root for each other," said Danica. "We really do!"