CHICAGO (CBS) — Jill Van Dyke graduated from Chicago Christian High School in Palos Heights just days ago. As the youngest of six children, she says competition is in her blood.

“My two brothers compete against each other all the time and me and my sister always compete. We always try to beat each others times,” Van Dyke said.

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Jill Van Dyke’s family helps her prepare for her first Ironman. (Photo provided to WBBM)

On Sunday, she and her brothers will be competing in the Wisconsin Ironman. At 18-years old, she’ll be the youngest competitor there.

“My two older brothers and old sister competed in a half Ironman a couple of years ago. My brother was actually one of the youngest competitors so when I turned 18, I knew I wanted to try,” she said.

Jill Van Dyke has been training for the Ironman for a year. (Photo provided to WBBM)

She’s been training for the last year and she ran cross country and track in high school.

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“My brothers have been working with me over the last several months. I think I’m ready,” she said. “My friends think we’re kinda crazy. I think they’re shocked I’m doing this so I kinda want to prove them wrong and do it.”

Jill Van Dyke running at her state cross country meet last fall. (Photo provided to WBBM)

The Ironman is a 1.2-mile swim, a 56-mile bike ride and a 13.1-mile run. Van Dyke said leading up to Sunday, she’ll be getting lots of rest, and watching her nutrition.

“I have to prepare myself and make sure I have enough fuel in my body so I can last,” she laughed.

Jill Van Dyke and her brothers training for the Ironman. (Photo provided to WBBM)

She hopes to complete the race in 7 hours.

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Ironman races are held around the world. She said her next goal is to compete in other cities.