By Henry Hanks CNN
(CNN) -- Adam Park considers himself lucky.
He weighed 315 pounds at 15, but didn't run into trouble with bullies or pressure from family and friends.
But he knew that he was not living the life of most teenagers. He didn't go swimming or sleep at friends' houses. He wouldn't get on rides at the fair, feeling self-conscious and afraid that he wouldn't fit.
On his own, he knew he had to make a change.
"I educated myself on the healthy choices in life," said the resident of Bowmanville, Ontario.
"My parents got me a treadmill. When I started, I could only do 10 minutes at a speed of 2.5 (miles per hour) and (then) cut out all of my snacks and pop."
Soon, he noticed his energy level increasing and tried to challenge himself by increasing his treadmill time to 20 minutes and his speed to 3 mph.
The weight really started to come off. He ate protein sandwiches at school and added an exercise bike to his routine. After losing 75 pounds, he felt good about joining a gym.
"Adam is a shy guy and never wanted to bring attention to himself, so when he started, he did it quietly," his mother, Charlene Park, said.
But at this point, there was a stop in the progress, as trainer Aaron Adu Poku noted.
"When Adam first came into the gym, I noticed a young man with his head down, low monotone voice and a confidence that was almost nonexistent," he said. "On the first day I trained him, he rarely spoke to me, and barely looked me in the eyes.
"I had to train Adam in a private room because he was too shy to workout in the main section of the gym. It was difficult to train Adam at first, because we had to start from basics and improve his form in all areas relating to exercises, such as proper posture, squatting techniques and so forth, although this is the case for all new beginners. The first month was Adam's hardest month."
After working at it with Poku, Park noticed a weight loss of 10 pounds and his confidence improved, soon moving into the public gym.
"He spoke with conviction and smiled at everyone," Poku said.
"Once we stopped training in the private room and started working out in the main gym, Adam's weight loss accelerated beyond my expectations. His nutrition was on point, his form for every exercise we did was flawless, and he had 10 times more stamina than when he first walked into the gym.
"Six months after training him, I saw a brand new young man that I had never seen before."
Now, just over a year later at 17, he weighs in at 150 pounds, his weight loss goal, a dramatic drop of 165 pounds. His girlfriend, Claire, often joins him in his exercise routine.
To maintain the weight loss, Park drinks five to six bottles of water a day, eats fruit and granola for breakfast and continues with protein for lunch.
"I want (other teenagers) to see that hard work pays off, and that they can make this change in their lives as I did," he said.
He even conquered his fear of roller coasters at the fair.
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