Terry Fox is one of Canada's most recognizable heroes, with generations of Canadians having seen archival footage of his iconic 1980 run, as he crossed the country to raise awareness and money for cancer research.

But , a new documentary that premiered at the Toronto International Film Festival last month, makes the case that there is still much to learn about the young man behind the Marathon of Hope.

Directed by Sean Menard, the film draws on 96 reels of previously unseen footage, bringing Fox's voice, humour, frustrations and determination to the screen.

Run Terry Run, the upcoming Terry Fox documentary, has a new trailer PhotosIN PHOTOS | TIFF movies and moments Menard, who previously made the self-funded MuchMusic documentary , was inspired to search for first-hand documentation of Fox's marathon due to the limited amount of high-quality footage available. Aided by the Terry Fox Foundation, he discovered the footage in a Toronto storage unit a few blocks from his own home. He subsequently restored the reels of film to 4K quality and used it to make his film. Here are some of the things we learned from the documentary.

1. Terry Fox didn't reach his destination — but he ran thousands of kilometres for his cause Fox's goal was to run from St. John's to Victoria, a total distance of about 8,000 kilometres. He planned to cover about 42 kilometres — the distance of a marathon — each day.

In Ontario, however, he made several detours to speak at rallies, meet supporters and promote cancer research. Those stops meant he did not travel as far west as he might have on a more direct route — perhaps reaching Manitoba or Saskatchewan — but they did help turn the Marathon of Hope into a national movement.

He was forced to stop near Thunder Bay, Ont., on Sept. 1, 1980, after learning that the cancer had spread to his lungs. By then, he had run 5,373 kilometres in 143 days.

2. Terry Fox and his best friend fought, so Fox's younger brother joined the journey Terry Fox and his best friend, Doug Alward, began the Marathon of Hope in St. John's on April 12, 1980, but the physical demands of the run and the strain of living together in a van had created tension.

Terry's younger brother, Darrell Fox, then 17, joined them in New Brunswick in May. He helped ease the friction between the two friends by acting as a mediator.

3. He was frustrated by some media coverage Fox cared deeply about how journalists portrayed him and the Marathon of Hope. He became frustrated when stories failed to capture the purpose of his run, particularly when they focused on disagreements with Alward or Darrell.

Before Terry became a national figure, Toronto Star journalist Leslie Scrivener documented his journey in a weekly column called . Her reports helped build public support for the run, which grew from a cause many people initially doubted into a national movement.

4. He did not want sponsorship money for himself Terry was determined that money raised throughout his run would go to cancer research. He did not want to accept sponsorship money or personal financial support.

But organizations began helping in other ways. The Canadian Cancer Society hired a publicist named Bill Vigars, Ford donated a van and Adidas provided running shoes.

The public campaign also inspired music. Country singer Nancy Ryan recorded , written by Vern Kennedy, with proceeds donated to the Canadian Cancer Society.

5. He thought a car accident contributed to his cancer When Terry was 18, he was involved in a car accident that he believed caused or contributed to the cancer in his right knee.

Doctors, however, told him there was no connection between the accident and his osteosarcoma — a rare and aggressive form of bone cancer.

The pain he experienced after the crash was an early symptom of the disease, which was diagnosed in 1977 and ultimately led to the amputation of his right leg.

6. He drew inspiration from other children with cancer Terry's experience recovering in hospital, including watching other young patients die from cancer, helped shape his decision to run across Canada.

The film shows how Terry wanted the Marathon of Hope to give people affected by cancer a sense that something could be done. His goal was to raise money for research so future patients would have better treatment options.

7. He disliked going to the doctor and avoided it Terry Fox was determined and disciplined, but he did not enjoy medical appointments. The documentary reveals a young man who resisted seeing doctors and did not want to be defined by his illness.

8. He had a complicated relationship with his prosthetic leg As Terry lost weight during the run, his prosthetic leg became increasingly difficult and painful to wear. Because it no longer fit properly, it caused friction against his stump, and he needed to have it replaced. In one particularly difficult moment, Terry becomes angry after someone notices blood running down his leg.

The documentary footage captures the growing strain between Terry's changing physical condition and his determination to keep running.

9. Quebec was a difficult part of the journey Terry was frustrated by his experience in Quebec, where the language barrier made communication more difficult. Many drivers were unaware of the Marathon of Hope and repeatedly forced him off the road. Concerned for his safety, Alward and Darrell urged Terry to wear a safety vest, but he refused because he wanted people to see his Marathon of Hope shirt.

Ontario brought a different challenge. By then, public attention had become overwhelming. Terry was no longer simply a young man running along the highway — he had become a national celebrity.

10. He could still let loose despite the seriousness of his mission The footage also shows Terry's playful side. He jokes with Darrell and Alward, pulls pranks and enjoys moments of levity.

The film includes a particularly touching moment in which Terry is able to relax and connect with a young boy who also had a leg amputation. It is a reminder that Terry Fox was still a 21-year-old who could laugh, play and be silly.

11. Darrell Fox did not know his brother had gone to the hospital On Sept. 1, 1980, in Thunder Bay, Ont., Terry was having trouble breathing and told Alward to drive him to the nearest hospital. Darrell, who was travelling in a support vehicle behind them, initially thought it was a regular stop. He didn't realize this would be the end of the Marathon of Hope.

For 93 days, Darrell had known where his brother was at almost every moment. Suddenly his brother was nowhere to be seen. When Darrell arrived at the hospital, he learned that the cancer had spread to Fox's lungs.

At the hospital, Darrell says the roles were suddenly reversed. "It was Terry that was trying to comfort me," he told CBC News. "He had already accepted it and was thinking of the positive somehow — that this will only give more meaning to what [he's] just accomplished.

"I think that defines who Terry Fox is, always thinking of others and not himself," he added.

Terry Fox's legacy Terry died nine months later, in June 1981 at age 22, but the fundraising campaign he started continues worldwide. Annual Terry Fox runs, which take place in Canadian communities and at schools each fall, have raised more than $1 billion for cancer research.

Honoured with the Order of Canada at 22, Terry Fox remains an inspiration. His brother Darrell hopes audiences leave the new documentary with the sense that his brother's example is not impossible to follow.

"Terry was just an average guy," he said. "But look what he did. Look what he accomplished." opens in theatres on Oct. 9.