When Shannon Thompson crossed the finish line after her first Ironman, she saw how much energy a challenge like that can generate.

“You get to see the best in humanity,” Thompson said. “It’s just people wishing the best for other people in an in-your-face-out-loud way. It’s a real privilege to be in that.”

She also saw that she could use the support she’d received to do something for others.

“I was so blown away by the breadth and depth of support that I received,” Thompson said. “During my training, through my blog. All of these people read it and said nice things to me and followed me through this race. I mean they were tracking me while I was racing and I came over that finish line and picked up my phone and I had 146 Facebook notifications from people who’d been watching me all day. And then I sat there and watched all these people go, ‘you just finished, you just finished!’”

Thompson was grateful for all the support she received, from friends, family, fans and training partners.

“But there are people that need that more than I need it,” she said. “So if I can take that support and leverage it and make it bigger — because this whole thing is bigger than me anyway — I want to turn it into something that makes a difference for a lot of people.”

For Thompson, making it bigger means challenging her supporters and friends to help her raise $10,000 for the Patrick Dempsey Center for Cancer Hope and Healing through their annual fundraising event, the Dempsey Challenge.

The Dempsey Center is in Lewiston. It provides free support to patients suffering from cancer, with everything from support groups to massage. Actor Patrick Dempsey and his siblings founded the organization with the Central Maine Medical Center in honor of their mother, who passed away from cancer.

The Dempsey Challenge allows competitors to choose between a 5K and a 10K walk or run on Saturday, and between various distances for a bike ride on Sunday. After her Ironman, Thompson knew she wanted to really challenge herself.

“I want it to be hard. I want to raise a ton of money for this organization,” Thompson said.

She plans to ride her bike up to Lewiston on the Friday before the Challenge, a distance of about 75 miles. Then she will do the 10K run on Saturday, and the 100-mile bike ride on Sunday.

“I just decided to make it as hard as I possibly could within reason,” Thompson said. “The hardest thing I could come up with that I thought I could actually do. And based on how I feel right now I’m a little worried. But I’m going to do it.”

Thompson has a lot of reasons for choosing the Dempsey Challenge.

“At a very basic level I really love the Dempsey Center, and what they do and how they do it. They are incredibly loving. The way they run that place and the way that the people who work there interact with the people who rely on it is so—they’re really professional, and they manage to operate from this place of unconditional love,” Thompson said. “It’s really hug-y, it’s call-me-at-home. Somehow they strike that fine balance of having good boundaries and operating in a completely functional and healthy way while also extending themselves to people in a way that most organizations can’t do. There’s just some magic there.”

Thompson has seen that magic work for a friend of hers, another cyclist, who relied on the Dempsey Center after his cancer came back. She also has family members who have suffered because of cancer.

“Everybody has connections to cancer,” Thompson said. “I had a niece who died three and a half years ago. She had brain tumors. So that drives a special interest in trying some way to help people who are struggling with cancer.”

Last year, her brother and sister-in-law, her niece Phoebe’s parents, agreed to match a $1,000 donation if Thompson and her supporters could raise that much in a week. They managed it in a day. This year, Thompson said, her brother has agreed to match all donations, up to an unspecified but substantial amount, given on Phoebe’s birthday, Thursday, Aug. 28.

Thompson realized through her Ironman experience that, as hard as it was to complete a 140.6 mile triathlon, she has been lucky.

“One of the things that I’ve been acutely aware of through this process is how incredibly lucky I am that I’m choosing the challenges that I face,” she said. “I took on the most challenging task I’ve ever taken on, and that’s an incredible luxury, to be able to do that, and to not be in the position of responding to challenges that just landed on me. I can’t even tell you the depth of my gratitude for being in this position.”

Thompson knows she’ll be faced by challenges outside of her control, but when she is lucky enough to choose, she’s chosen the Dempsey Challenge.

For more information on the Dempsey Center, click here. To view Shannon Thompson’s Dempsey Challenge donation page, click here.