Karen Vornkahl doesn’t expect to be at the front of the pack in Sunday’s Louisiana Marathon.

For her first 26.2-mile run, Vornkahl is focused on crossing the finish line.

She compares the effort with the 20 months she focused on losing 150 pounds.

“It didn’t matter when I got there,” said the 57-year-old runner. “It just mattered that I got there.”

A little more than three years ago, Vornkahl, the owner of the Baton Rouge Court Reporting School, never thought about running. Then, the 5-foot-7-inch mother of two weighed 300 pounds.

She would drive in circles looking for close parking spots and dreaded the thought of climbing stairs.

While Vornkahl had small successes with a few different diet programs, she could never keep the weight off until November 2011.

“I hadn’t been on the scale in a long time, but I knew it was bad,” she said. “It was that kind of feeling where you get out of bed in the morning and you’re just tired. I was so tired.”

That year, on Thanksgiving Day, as her husband, son and daughter ran the Turkey Trot 5K in downtown Baton Rouge, Vornkahl quietly decided to start eating less and move around a little bit more. She started tracking her calories with a smartphone app and lost a few pounds.

After a month, she had dropped 20 pounds and moved a treadmill next to her favorite chair in the living room.

She decided she would walk for at least five minutes everyday. Most days the five minutes turned into 20 or 30.

Dropping 150 pounds was her goal, but she doubted it would happen.

“I thought there was really no way to actually lose that, but I did,” she said. “I stayed with it. As I began to feel better and lighter on my feet, and I got encouragement from people, then I got better at it.”

After seven months of walking on the treadmill and changing her eating habits, Vornkahl had lost 70 pounds. She joined the gym where her husband worked out and hired a trainer.

“I learned to lift weights,” she said. “I can do pushups. I can do ‘boy pushups.’ ”

A year later, on Thanksgiving Day 2012, Vornkahl ran the Turkey Trot, her first 5K. She weighed 200 pounds.

She hit her target weight of 150 pounds in July 2013.

Now, exercising every day and eating healthy have become part of her lifestyle — not just weight-loss techniques.

In addition to running, she and her husband started bicycling. In the past two years, they have ridden a two-day, 150-mile bike ride as a fundraiser for the National Multiple Sclerosis Society — the hardest thing Vornkahl says she has done so far.

“I can handle being wet, cold and miserable,” she said. “I never knew that about myself. It turns out I’m a little tougher than I’ve ever thought.”

Last year, Vornkahl ran the half-marathon during the Louisiana Marathon weekend, and she has finished a few other 13.1-mile races as well.

Sunday’s race will be a new test.

“I can gut it out for however long it takes,” said Vornkahl, who has suffered a few injuries while training. “It’s going to be a gut-it-out kind of thing. All along I said in my head and in my heart, ‘I think I’m strong enough to do it.’ It’s whether the knees and feet agree with me, that remains to be seen. They might have other ideas about it.”

No matter how she finishes at the marathon, Vornkahl will run with a confidence she did not have three years ago.

“I like that I’m strong,” she said. “I’ve got some muscles and stuff, and I’ve got to use them.”