One of Steve Jobs' closest friends and business allies has said the former Apple boss's own self-belief and mindset led him to put off having his cancer treated.
Avie Tevanian said Mr Jobs had a "reality distortion field" - a force of will that helped him get people to achieve the impossible.
That same belief system caused him to refuse conventional treatment for his cancer in the critical early stages after diagnosis.
He decided instead to explore alternative therapies and go on a special diet.
Mr Tevanian said: "Steve was an unconventional person and when it came to treating his illness he was very happy to use non-traditional methods.
"I think he truly thought that through some unconventional means he could cure himself."Initial diagnosis
Mr Jobs, the co-founder of Apple, died aged 56 on 5 October 2011 - eight years after first being diagnosed with a rare form of pancreatic cancer.
He was diagnosed with insulinoma, which unlike other pancreatic cancers, is curable and can be treated with surgery.
Doctors recommended an early operation but Mr Jobs could not be persuaded to stop his pursuit of alternative remedies.
"Being Steve, it was easy for him to find people who would agree that it was worth a try.
"Many of us around him, myself included, his wife and other people were saying: 'Steve, you know, maybe you should just have some surgery here and get it over with,'" said Mr Tevanian, who was chief technology officer at Apple until 2006 and a long-standing friend of Mr Jobs - even organising his stag party.
"He was the kind of person that could convince himself of things that weren't necessarily true or necessarily easy, maybe easy is the better way to think of it.
"That always worked with him for designing products, where he could go to people and ask them to do something that they thought was impossible.
"But he would keep asking and say: 'You know, it's impossible but I still want you to try' - and because of his sheer will, they would actually make it happen, or make something like it happen."Mistaken delay
Mr Jobs went public about his cancer in 2004 after finally agreeing to surgery that year, by which time the cancer had spread.
He realised the delay had been a mistake and told his biographer Walter Isaacson: "I should have gotten it earlier."
Mr Tevanian said he had expected the Apple boss to pull back from work but the opposite happened.
"He started working even harder. It's almost as if he knew his time was now limited.
"There was a lot more that he wanted to get done. Everything that he did, everywhere he worked just became magnified."
Despite continuing health problems, Jobs continued to work even after undergoing a liver transplant in 2009.
He finally went on medical leave in January 2011, before formally resigning as CEO of Apple in August.
Steve Jobs: Billion Dollar Hippy is available online via BBC iPlayer at the above link (UK only).