Watch This 577-Pound Man Finish a 5K Race and Crush His Goal

At 577 pounds, Derek Mitchell may not look like he's in terrific shape but he's dreaming of something big. He dream is to finish a 5K race.

He wasn't always this heavy. When he turned 13, he started gaining an incredible amount of weight and nobody could figure out why.

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He told INSIDE EDITION, “I hit 100, 200, 300, 400, and so forth.”

Derek was eventually diagnosed with a non-cancerous tumor on his pituitary gland that was blocking his body's ability to produce testosterone.

Now, his sister Gina, was determined to help her brother lose weight by encouraging him to enter the 5K race in Kansas City.

She said, “It was a battle.I nagged at him quite a bit.”

On race day, Derek was pumped and ready to go. He said, “Beautiful morning for a run.”

He was off and his sister was right there with him.

Derek may have been at the back of the pack, but at least the finish line was in sight. Derek hoisted an American flag high and suddenly his walk turned into a sprint.

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He was aiming to break one hour and 20 minutes.

Derek was breathless when he crosses the finish line and he broke his goal. He finished the race at one hour and 19 minutes and 17 seconds.  

A big victory for a big guy with an even bigger heart.