Kate Gosselin has revealed her reason behind running the Rock n' Roll Las Vegas Marathon over the weekend.

The 36-year-old reality star finished the 26.2 mile race in four hours, 59 minutes and 21 seconds.

Kate says completing her first marathon was not easy but she felt she had something to prove.

"I'm not one to do anything lightly," Kate told People magazine. "I either do it or I kill it. I guess this is considered killing it."

Kate has been a runner for three years and has got into amazing shape with exercising around her neighbourhood in sometimes below-freezing temperatures.

The former Dancing With The Stars contestant said she also wanted to do the race to teach her eight children a lesson.

"I'm running this because I want to show that with dedication and determination anything is possible," she revealed.

"I want them to remember this moment when their mom completed a marathon, knowing that nothing in life should stop them from attaining their goals."

"This will probably be one of the most painful messages I will ever impart to them."