PORTLAND -- If I m committed to something. I m committed 1,000 percent, explained 42-year-old Mark Eisenhart, the man some call the weight-loss ninja.

He s committed at the gym and in the kitchen. Eisenhart vows never to return to what almost killed him,

I was more than fat. I was morbidly obese, I weighed 455 pounds, he said just before a workout at Giant s Gym in Northeast Portland. His weight-loss journey began a month after the death of his dad.

I was thinking about how awful it felt to be in this body. I had low back pain, a low energy level and I was sleeping as much as 14 hours a day.

Mark knew what it was like to be fit. He had been a paramedic and firefighter and played football in high school.

A month after his dad s passing, he made a promise to his Mom and sister.

I told them that I was going to make getting and staying healthy my full-time job and my highest priority, remembered Eisenhart.

He wasn t kidding when he said full-time. Mark now works out six days a week sometimes three times in the same day.

More than a dozen sponsors help pay the bills but he keeps things simple with a shared kitchen and a single, rented room.

You ll see Mark on the NBC program American Ninjas next month. He ll be competing on the obstacle courses. He s also had bit parts on the television shows Leverage and Grimm.

Now weighing 250, he believes a career as an actor is possible.

It s about getting a second chance to live my life over again.

At 42, he watches what he eats and remembers the changes in diet that helped him drop the weight.

White sugar was out, white rice out, while flour was also removed from my diet completely.

Mark is now vegan and eats 80 percent of his food raw. Kale is a favorite which he puts in a shake with water, apple, avocado, lemon and lime. He knows his routine may seem like an obsession, but prefers to think of it as a passion which might inspire others.

What I ve been trying to do is pay my message forward, because I believe what worked for me can work for other people, concluded Eisenhart.

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