When her 21-year-old sister was diagnosed with leukaemia, Bermudian Kristen Midon knew she was right to break her vow never to run another marathon and started training in earnest.

In doing so, she not only pushed through to complete this year's Disney Marathon — her second conquest of the 26.2-mile distance — but in the process became the biggest individual fund-raiser for the Leukaemia and Lymphoma Society's Team-in-Training programme across the entire US, as she collected $38,000.

And Kristen's friend and fellow Bermudian Allison Petty chipped in with a further $12,000, as she also competed in Florida, in her case completing her first marathon.

Running a marathon, and particularly one on a hot and humid day in Florida after spending months training in the chilly environs of Manhattan, is impressive enough for Kristen and Allison, who are both in their 20s.

The ability of both Islanders to eclipse the minimum Team-in-Training (TNT) requirement of $3,800 with a combined contribution to the Leukaemia and Lymphoma Society of $50,000 was a stunning achievement.

At the heart of it all is Kristen's sister Stephanie, 22. Today, she is almost half-way through chemotherapy treatment to combat acute lymphoblastic leukaemia (ALL).

Stephanie's treatment is succeeding, and she is in remission. And, while she prefers at this time to avoid the media spotlight, she also recognises the tremendous efforts of her sister and Allison in raising so much to help those who are affected by leukaemia, and doing so by running for more than four hours on a hot day.

"I could not be prouder of them," she said. "Their fundraising was incredible, and it really makes a difference. Only 50 years ago my diagnosis would have been considered fatal, but today it is curable thanks to the research and progress made through grants and fundraising.

"The Leukaemia & Lymphoma Society does an incredible job supporting everyone affected by these diseases whether it is patients and their family members, or doctors and researchers."

It was April last year when Stephanie was diagnosed. Around the same time, her sister Kristen was toying with the idea of running a second marathon, despite vowing "never again" after the Nashville Marathon a year earlier.

A friend from high school who was a keen runner and had run the Disney race on her 21st birthday wanted Kristen to join her for a re-run as they both turned 25. When Stephanie was diagnosed with ALL, Kristen found she had a further reason to don her long-distance running shoes again and signed up with the New York City Chapter of TNT to get encouragement, advice and training companionship.

Working in Manhattan for experiential marketing agency, Jack Morton Worldwide, she was soon joined by friend Allison, who works in the New York office of Bermuda reinsurer Security Capital Assurance.

Together they trained in Central Park with the 100-plus person TNT group.

"The fall was a tough time for Stephanie. Despite being several months into her two years of chemotherapy, the treatment ahead seemed endless. I put the big push on my fundraising then, which gave my family and Stephanie something really positive to focus on. We would all e-mail each other excitedly as more and more donations came in and my total number kept rising," said Kristen.

Team-in-Training runners are required to raise a minimum of $3,800 for the Leukaemia and Lymphoma Society. By Thanksgiving Day 2007, Kristen had secured pledges totalling $12,000 from family and friends.

"I decided then to set $22,000 as my goal; $1,000 per year of Stephanie's life. At the time, my family and I thought it was really aggressive, but I knew that Stephanie's strong attitude had positively affected a lot of people, and I hoped that that might cause them to donate to the Leukaemia and Lymphoma Society in her honour," she said.

Yet that lofty mark was soon surpassed as Kristen's total more than tripled.

While the fundraising side was going so well, there was still the training to do. The autumn and winter in New York can be bitterly cold. And it was.

Kristen and Allison, 26, stuck with the training programme and the companionship.

For Allison, it was a step into the unknown, even though she comes from a family of runners. She had run May 24 before and last year joined her dad in a half-Ironman event in Vermont.

When race day arrived, Allison and Kristen awoke in the middle of the night in order to catch a bus at 3.15 a.m. to the start line in Epcot, where 18,000 runners set off at 6 a.m.

"It was hot and high humidity. I never drink water when I run, but in this race I couldn't get enough water in me," Allison remembers.

The two friends had agreed that each would run at their own pace.

"We had different pace levels and we were in different starting corrals. Our coach had told us that trying to keep up with someone in a marathon by running faster or slower than we would normally was more likely to lead to injury."

The marathon course was full of marvellous sights, passing through the Disney Magic Kingdom, Animal Kingdom and on to MGM. The only 'boring' section was a non-descript four miles on the highway between miles 18 and 22, which Allison found the hardest part of the race.

Earlier, around mile 15, she had traded paces with well-known Bermuda runner Giorgio Zanol.

"The last 385 yards felt like another mile. Kristen's sister was there at the finish. I had so many feelings coming across the finish line. There were tears in my eyes, not just for the cause, but for all the people who had believed in us," she said.

Allison finished in four hours 13 minutes. Kristen was still out on the course and finished in 4:46 — a 20 minute improvement on her debut marathon — but slower than she had hoped.

As it turned out, all TNT runners from New York who ran the Disney Marathon had slower times than anticipated because of the conditions. The TNT runners who ran in less humid conditions in the Arizona Marathon the same day hit their targets.

Kristen said: "It was tough training in New York in the winter in the cold and then having the heat and humidity in Florida. I had not prepared myself mentally enough and made the mistake our coaches had told us numerous times not to do: going off too fast over the first ten miles."

Kristen's parents were at the finish line, as was her younger brother, older sister and Stephanie. The family celebrated the momentous weekend by spending the following two days at the Disney World parks.

For Kristen and Allison, the achievement was all the more satisfying knowing they had raised so much for an organisation that touches the lives of so many battling Leukaemia and other blood cancers, including Stephanie — their inspiration every step of the 26.2 race miles and the hundreds of miles of training that went before.