DOUGLASVILLE, Georgia (CNN) -- Like many young girls, Jennifer Marnell always dreamed that one day she'd become famous.

Jennifer Marnell once maxed out at 300 pounds. She lost 180 pounds and is now a fitness instructor.

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Bubbling with personality and quite the ham -- she was no stranger to performing. Marnell loved singing, dancing and acting in local plays while growing up on the outskirts of Atlanta, Georgia.

Even though her family showered her with adoration and unconditional support -- Marnell was hiding something that she was afraid to share with anyone.

Since the age of 8, she struggled with her weight.

"I was the only one in the whole family who was overweight," Marnell recalled. "[They] were always supportive and told me I was beautiful ... I didn't realize how depressed I was because my family loved me no matter what."

But other people weren't so nice. Marnell says classmates and other people teased or ridiculed her about her weight. Instead of talking about her feelings -- she turned to food for comfort.

As she ate to soothe her pain -- Marnell's weight spiraled out of control. Watch more on Jennifer Marnell's journey »

"It got out of control over the years because it became an addiction," said Marnell. "Food didn't talk back to me and didn't tell me no ... I didn't know how to stop and listen to my body."

Working as a nanny at the age of 27, Marnell was 5-foot-tall and weighed 300 pounds.

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The wife and mother says a series of embarrassing moments such as not fitting into a restaurant booth, running out of breath while walking and lacking the energy to play ball or skate with her daughter -- took an emotional and physical toll on her health. But the final straw came during a trip to an amusement park with her family.

"We were at Six Flags waiting on a ride and we waited for an hour-and-a-half," said Marnell. "When we got on, I couldn't latch the belts because I was too big and they had to ask me to get off."

Devastated by the incident, Marnell says she broke down in tears and had a heart-to-heart talk with herself. Afraid that she might die before the age of 30, she was tired of being a "fat mom" and wanted to set a good example for her daughter.

After the mental pep-talk, Marnell started her weight loss journey by joining a gym. She started by exercising in the women's-only section and ate a low-fat, low-calorie diet. After a few months, she'd lost 50 pounds. The weight loss boosted her confidence and she decided to try a water aerobics class which was a lot less stressful on her bones and joints.

Over the next two years, Marnell continued taking group fitness classes, hired a personal trainer to get past a plateau and eventually lost 180 pounds. CNN I-Reporters share weight loss photos »

After reaching her goal weight of 120 pounds, she decided to start a new career as a fitness instructor and provides personal training advice on her Web site One of the most important lessons she's conquered is emotional eating.

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"You've got to learn to talk through your problems instead of using food," Marnell says. "An alcoholic can't just have one drink. I will never eat a Snickers bar because that is my one weakness ... the one thing I won't have."

The weight loss has also helped her realize another dream -- being in the limelight.

In January, she was featured on the "Oprah Winfrey Show" and in People Magazine's "Half Their Size" issue and will appear on the game show "Don't Forget the Lyrics" with Wayne Brady. She's also touring the country as a spokesperson for Gold's Gym and has just inked a book deal to tell her weight-loss story.

Marnell says all of the recent attention has been a bit overwhelming but she's enjoying every minute of her new career and life.

"It's made life more exciting," said Marnell. "I still feel like the same person on the inside, I have the same heart. But the outside, it's just enhanced the inside even more."

What advice does she have for other people who want to lose weight?

The toughest part of losing weight, according to Marnell, is staying mentally focused. She recommends taking "baby steps," trying not to do everything at once or focus on how much you have to lose and joining an online support group.

"Learn to accept yourself for who you are," Marnell advises. "It can be done ... it's not going to be easy -- but it can be done."

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