A Portland man is on a mission to change lives after changing his own in a dramatic way: He lost 200 pounds.

I was more than fat, he said. I was morbidly obese. I weighed 455 pounds.

Mark Eisenhart's weight loss journey began a month after his father died. He promised his mom and sister he would make getting and staying healthy his full-time job, and he wasn't kidding.

The 42-year-old now works out six days a week - sometimes three times a day.

More than a dozen sponsors help pay the bills.

His success inspired him to launch an acting career and he's already had parts on Grimm and Leverage. And you'll soon see Mark competing on the obstacle courses of American Ninja.

It's about getting a second chance to live my life over again, he said. What I've been trying to do is pay my message forward because I believe what worked for me can work for other people.

Mark is now vegan and eats 80 percent of his food raw. He knows his routine borders on an obsession, but prefers to call it a passion, which he hopes can inspire others.

You can watch Mark on American Ninja on NBC next month.

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