ATLANTA, Georgia (CNN) -- Two years ago, Tim Lenczowski dreaded walking from the parking lot into his office.
Tim Lenczowski had heart problems before losing 128 pounds in Operation Boot Camp.
Weighing 335 pounds, Lenczowski suffered constantly from pain in his knees and ankles. Everyday activities such as walking and even traveling on an airplane had become difficult.
At the age of 39, he was diagnosed with a heart condition and hypertension (high blood pressure). He knew it was time to make a change and his doctor agreed.
"It was a chore to get to work. I had to park and then walk," says Lenczowski. "By the time I got to work I was sweating and I would have to time things so I could cool off before I had a meeting."
The extra weight not only took a toll on his physical health, but also was chipping away at his self-esteem. Lenczowski, who worked as a fundraiser for a nonprofit health organization, felt like a hypocrite. Watch Tim's incredible weight loss success story »
"People would see me then ... they didn't respect me," remembers Lenczowski. "How could I ask for money to support [the foundation] without practicing what I preached?"
Find a plan that works for you
Try different programs to find the one that works for you. Take time to talk to the instructors and students to get a feel for the program and if it is right for you. Don't be afraid to change if it's not working for you.
Build a support system
You should not go at this alone. Rely on your friends and family to help support you every step of the way. Make sure your physician is part of your support team. Another great support system can come from a group workout program.
Keep yourself accountable and track your successes. This will motivate you as you see how far you've come and set new goals. Celebrate every success along the way!
Keep yourself challenged
Once you get moving, make sure to keep pushing yourself to try new things, whether it's running your first race or taking a yoga class. Get out of your comfort zone and try something new.
Get your mind in the game
Losing weight and getting fit is a mental workout as much as a physical one. Make sure your mind is in the game and work to overcome the mental obstacles that come your way. Challenge the little voice inside you to keep pushing your body.
My success was possible by making a lifestyle change and sticking to it. Making the workouts fun and enjoying the foods you eat will be much more enjoyable and help you stick with it in the long run.
Lenczowski struggled with weight for most of his life. He tried just about "every diet imaginable" and though he lost weight on some, he would always gain it back. A sedentary lifestyle and fast-food diet had caught up with him and as his 40th birthday approached, he'd become fed up and realized he didn't want to live out the next half of his life as a fat person.
Not knowing where to start, Lenczowski started walking because it was low impact. He walked a marathon and though it took him nine hours to complete, Lenczowski says he made some great friends in the process. After the race, the same friends asked him to try kickboxing.
"The thought of going to a gym was intimidating enough, but kickboxing?" Lenczowski recalls. "My friends kept on me until I caved and reluctantly decided to try it."
The first time he went to the class, Lenczowski says he sat in the parking lot for a while trying to muster up enough courage to walk into the gym. But once inside, he says everyone welcomed him. In eight months of kickboxing, fat burning classes and watching his diet -- he'd lost 60 pounds.
Lenczowski says he was ecstatic and his friends began pushing him to take the next step to get in shape -- boot camp.
"They pushed me into boot camp and I loved it," Lenczowski says. "It's the hardest thing I've done."
Lenczowski joined Operation Boot Camp which offers a one month program to increase fitness through exercise and proper diet. With the support of his friends and by pushing and challenging himself each month to move from the back of the class to the front, he started to see results.
"When I went to boot camp, I couldn't run a mile. I set that goal for myself and the instructors helped," Lenczowski says. "I thought, 'If I can run a mile, can I run a half-marathon?' "
Eight months later he had lost a total of 120 pounds. To date, Lenczowski has run five full marathons and 12 half-marathons, accomplishments he would have thought impossible five years ago.
How has his life changed?
Achieving various fitness goals was a tremendous boost to Lenczowski's self-confidence. The physical accomplishments began to have a positive affect on other aspects of his life as he realized he could do anything he set his mind to. Since losing weight, he's become more outgoing, happier, moved closer to a park, changed jobs and become a fitness instructor. He recently bought his own boot camp franchise.
"I encourage people to take that first step. I know it's hard, but you have to find the right program," Lenczowski says.
The dramatic weight loss and healthier lifestyle has also improved Lenczowski's physical health. He's no longer on heart medication and his doctor has greatly reduced his blood pressure medicines.
Lenczowski says the biggest key to his success was his network of support from friends, doctors and fitness instructors. As he approaches his goal weight, he's set a new goal of passing his experience on to others who want to lose weight.
"I meet new people and they don't look at the old Tim. They look at the person sitting here now -- more confident, funny, loves to give back and that's what I want to be remembered for."
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CNN's Matt Sloane contributed to this report.