Jillian Michaels on her 'rock-bottom moment' and how fitness changed her life

Most people know fitness expert, author and entrepreneur Jillian Michaels as the personal trainer who pushed people to their limits on NBC’s The Biggest Loser. But not everyone knows that Michaels herself used to be overweight and fat-shamed as a kid.

“Food for me meant comfort,” Michaels shares with Yahoo Lifestyle. “It meant control. It was a way of bonding with my father, who was also overweight.”

When Michaels was 13, her parents were going through an “ugly” divorce. “My mom had the foresight to find me an outlet,” Michaels, who is now 44, says. “She thought karate would be great. I could be physical. I could be angry.”

But Michaels still wasn’t taking good care of her health, particularly when it came to her eating habits. “I showed up one day to a karate lesson with a bag of Cheetos, and I remember my martial arts instructor, who I, like, worshipped, looking at me with such disappointment,” she recalls. “That really hit me, that kind of rock-bottom moment of, ‘Wow, I’ve disappointed someone that believed in me.’ And it was the start of me starting to care.”

For her second-degree blue belt test in karate class, Michaels recalls having to break two boards with a side kick and thinking to herself that there was no way she’d be able to do it. She did — and it gave her a tremendous boost of confidence: “I showed up at school the next day just looking for a fight, just waiting for that person to make the cow sound at me, some comment about my body. And no one did.”

She continues, ”And I realized at that moment I felt differently about myself. I respected myself. And that’s when I became passionate about fitness as a means to help people transform their self-image and improve their self-worth.”

While she was training for her black belt at age 17, people kept coming up to Michaels at the gym, asking her how much she charged as a personal trainer. “I was like, ‘I’m not a trainer,’” she says. Michaels eventually started training a client — as she puts it, she “fell into it, loved it” — but didn’t make fitness her career until years later.

It wasn’t until she got fired from her desk job at a talent agency at 27 that she realized how far she’d come from what she “truly loved”: fitness. She opened a sports medicine facility and ended up on The Biggest Loser.

She then utilized her newfound platform to build her own brand. It’s her way of showing people “the path to health and wellness and empowerment that has worked for me and many others.”

Michaels, who shares two children — daughter Lukensia, 8, and son Phoenix, 6 — with ex-partner Heidi Rhoades, has a new book out, The 6 Keys: Unlock Your Genetic Potential for Ageless Strength, Health, and Beauty. “We all want to age well,” she says. “We want to look and feel great. After all, you can decide your weight. Why can’t you decide your age?”

When Michaels looks back on her life, she remembers her 13-year-old self and wishes she could send her a message. “Call it arrogant,” she says, “call it whatever you want. I would go back and tell that 13-year-old kid, ‘Life is going to be the s*** — just hang in there. And all of this builds character and strength. It’s going to take you so far in life.’”

Read more from Yahoo Lifestyle:

• This woman focused on getting healthy — and lost 167 pounds — for a touching reason: ‘I wanted to be a mom’

• One woman on coping with blindness and arthritis: ‘Joy is a choice’

• How 1 man feels after losing 117 pounds: ‘I still have body-image issues’

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