(CNN) -- Last year, Karen Daniel was feeling great about her weight. She had gone from 375 pounds to 200 in 24 months.
She was working out nine times a week and thrilled to have turned her life around. She no longer had to purchase two seats on an airplane. She went hot-air ballooning for the first time.
Daniel, one of Fit Nation's first success stories, said in February 2009, "Fit feels so good."
That feeling didn't last long.
Daniel started feeling bad after a trip to New York. She had a sinus infection, upper respiratory infection and bronchitis, she said recently from her home in Arizona. She started feeling better, but then got sick again. And healthy again. And sick again.
She went to two doctors who told her that her body was in "starvation mode," she said.
"I went way under on calories, and I got really sick," she said. "I went to under 1,000 calories a day, and I was working out between two and three hours a day. It was not a smart decision."
She felt like she was eating right, but she was gaining weight.
"It really is awful when you are doing everything you can and your body isn't cooperating," she said.
Daniel says by the time she had gotten her health back, she had gained 35 pounds. She needed to make changes again.
She now eats about 1,500 calories a day, more if she's had a hard workout. She decided to drop her trainer, and now she works out with her friends at a new gym. And she adds in new types of exercise, escaping the rut of cardio and lifting weights she felt that she was in, thanks to her workout buddies.
Her friend David, who is 71, teaches her boxing. Another friend who was a professional rower taught her that sport. She also wanted to try tai chi and yoga so she enrolled in classes to see if she would like them.
"I surrounded myself with positive people," she said. "If you surround yourself with people who sabotage you or people who don't believe in you, you're not going to go as far as you should."
Before she lost weight, she said, she knew certain foods were bad for her, but she had no idea how bad. So she learned about food and started paying attention to the number of calories. The cinnamon roll she used to eat had 800 calories. It'll be a great day when all restaurants start posting the number of calories in each menu item, she said.
Daniel runs a website, ihavebones.com, where she shares her story with other people who want to lose a lot of weight.
"It's so hard for them to make that first step, but no matter how many times you have to do it, it is so worth it," she said. "Being healthy is so worth it. It's so worth being able to do everything you want to do and not have to worry about things. I used to be worried about sitting in a chair because I might break it."
It just might take a few tries at that first step. Daniel said she took it a "million" times. The thing that held her back was self-doubt. Some of her restarts would last a day, some two days, some longer. She just kept trying.
And it finally worked, until she overdid it and got sick. The past year has been hard, she said, but she believes that even setbacks are part of the process of losing weight. She came out of starvation mode mentally stronger, she said. She's back on track, having shed 10 pounds in recent months.
She even gives lectures to fitness professionals to give insight into the mind of someone who is morbidly obese, telling the trainers they have to be more than just a coach.
"I tell them everything I have been through so they know what to look for and their clients don't go through the same thing," she said.
Her illness made her research more. She read more and tried new things in the kitchen and the gym. She keeps a food journal.
She shares those tips on the website and still exchanges email with scores of people who became aware of her story after the Fit Nation Summit in 2008.
She tells them about the doors that have been opened for her through her weight loss. She no longer has to make excuses. There are no more sudden illnesses that prevent her from going to an event because she won't fit in -- literally and figuratively. She went to a recent class reunion after missing so many. Her old classmates told her she looked the same as in high school.
"If you only knew," she thought to herself.
She laughs about it, and happily reflects on another recent event, a business trip/family vacation to Ireland, which to many people could have been considered a disaster. There was volcanic ash that trapped people on the island when they were set to fly home. And she had pneumonia.
"In my head I thought even with pneumonia I am a thousand percent better then I used to be," she said, adding that she still went sightseeing with her husband and two daughters. "I can't stress enough how much it means to me; of not sitting on the sidelines and being able to participate with my family. That is the biggest blessing I could have hoped for."