Derek Mitchell wasn’t the first person to cross the finish line Sunday.

Not even close.

But you wouldn’t have been able to tell that by looking at the grin on his face as he finished up his five kilometers in the annual Humana Rock ‘n’ Roll New Orleans Marathon.

For Mitchell, a 35-year-old Kansas City native, it was just about finishing ... period.

“There’s nothing like it,” Mitchell said. “There’s a sense of accomplishment when you cross the finish line. I did this, all of this, on my own. I had people here supporting me, but MY feet crossed the starting line and MY feet crossed the finish line.”

Mitchell ran the first few steps of the race, then walked most of the way down Esplanade Avenue into City Park. Then he ran the last 25 or so steps to complete his course, his latest accomplishment since his journey began last year on a day he’ll never forget.

That’s the day Mitchell got on the scale and saw those three numbers that changed his life.

625.

“It was just a surreal thing, Mitchell recalled. “I couldn’t believe I had let it get that far. But regardless of how I got there, I didn’t want to focus on all the things I did wrong or the things I could’ve done better. I wanted to just focus on the future and how I could move forward.”

He immediately came up with a plan, making a New Year’s resolution to start 2015: Stop drinking soda and start eating healthier.

His sister, a marathon runner, gave him another suggestion: exercising.

Mitchell obliged, starting off by simply walking to and from a stoplight right down the street from his home. It was only three-fourths of a mile round-trip, but it was a start.

He then decided to start doing at least one 5K race per month. His first one was last March. Then he did another one in April. Then two in May. Three more in June.

“And it just kind of exploded from there,” Mitchell said.

He ended up doing 21 5Ks and two 10Ks last year.

His goal for 2016 is to do 30 races.

Sunday’s was his fifth of the year.

Mitchell has dropped 80 pounds since his journey began last year, putting him at 545 pounds.

His goal this year is to drop eight pounds per month to lose 96 pounds this year.

The ultimate goal is to get to 225 pounds.

He’s dealt with his weight for close to 20 years, going back to his high school days.

“I just thought it was an eating problem and I tried to lose weight several times,” he said.

He’d lose 40 pounds, then stop. And then he’d get frustrated.

Five years ago, he discovered it wasn’t all his fault. He started having headaches and would sometimes black out, prompting him to go to the doctor. It was then that a non-cancerous tumor was found on his pituitary gland. The effects of the tumor made it even more difficult to lose weight.

“For the longest time I was using the medical part of it as a crutch,” Mitchell said. “But when I hit 625, I decided I was going to make the change, and I didn’t want to wait anymore.”

While Mitchell is subtracting the pounds, he’s adding the fans.

He has over 21,000 followers on his Facebook page — The Derek Mitchell Story. Many of those followers cheered him on along the way as they passed him by.

“I’m following you in Canada, you’re an inspiration to me,” said one lady.

“Are you the guy on the internet? Way to go buddy,” said another.

Even the music being played along the route seemed to play it’s part in rooting for Mitchell.

The ’70s tune “I Will Survive” blared just as Mitchell hit the corner of Esplanade and Treme.

Some gave him a high-five.

Letitia Williams of Atlanta stopped to take a picture with him.

One person watching the race, dressed in red, white and blue like the American flag Mitchell carried on his shoulders, walked a little bit with him just to chat.

Mitchell wore a yellow T-shirt with the words “Run for the Fallen” on the back.

He walked this race in memory of Trevor Pinnick, a soldier killed in Afghanistan in 2012.

But he didn’t just walk this race for Pinnick.

Derek also walked this race for Derek.

It was obvious by the smile he wore at the finish line.