Ronnie Corbett needed round-the-clock care and some days only managed to eat a few pieces of fruit, a single sweet and drink a glass of champagne, his wife said.
The comedian died on Thursday aged 85 having been diagnosed with a suspected form of motor neurone disease.
Corbett's wife of more than 50 years, Anne Hart, told family friend Michael Thornton that her husband "never once grumbled or complained" throughout his illness.
Writing in the Daily Mail, Mr Thornton said she told him: "No one could have been more courageous."
Corbett's illness began around Christmas 2014, at a time when Anne said he "started to feel unwell and found it hard to breathe and to lie down".
Recalling the moment the doctor diagnosed Corbett, she said they were told it was most likely to be amyotrophic lateral sclerosis, commonly known in the UK as motor neurone disease.
She told Mr Thornton it "knocked us both back", and if it had not been for Stephen Hawking - who suffers from the disease - and the Eddie Redmayne film about him, The Theory Of Everything, they would not have heard of it at all.
Talking about caring for Corbett, Anne said: "It became a 24-hour job, with Ron getting gradually weaker. He was not in pain, and up to the last 48 hours, he was fully conscious and aware of everything."
In his article Mr Thornton said it became harder to get the comedian to eat anything, adding that Anne told him: "Some days all he managed was a few pieces of melon, a glass of champagne, and a Liquorice Allsort. His weight dropped drastically and he simply began to fade away.
"But I would like people to know about the machine that kept him alive. It is called ResMed, a ventilator which helps people to breathe. Without that we would have lost him much sooner."
Describing what the much-loved entertainer meant to her, Anne told Mr Thornton: "Ron wasn't just my husband, and the love of my life. He was also my best friend."
Jimmy Tarbuck, 76, fought back tears as he told Good Morning Britain he was aware of Corbett's illness.
Asked if he knew he had motor neurone disease, Tarbuck said: "Yes I did know he wasn't very well, and I knew exactly ... sorry I'm getting a bit choked ... what he had.
"And he didn't want to see you. He said 'I don't want to see you like this', but I'd speak to him on the phone. And when you did anything with him or for him, you always got a letter from him, that's how correct he was. But yes I did know, unfortunately, that he wasn't very well."
Meanwhile, officials were reportedly considering honouring Corbett with a knighthood, and it is understood a panel that bestows the titles had received letters from famous names in support of his nomination, and if approved he could have become Sir Ronnie in the Queen's 90th Birthday Honours.
Mr Thornton said he contacted the Cabinet Office to propose a knighthood "several months ago".
He said there was a "virtual stampede on the part of celebrated figures" when it came to gathering letters in support of the nomination.
According to The Daily Telegraph, a low-key campaign led by comedian David Walliams to include Corbett on the Queen's Birthday Honours List was launched amid concerns over his deteriorating health.
Downton Abbey creator Lord Fellowes, who sits on the arts and media honours committee, told the newspaper he thought "he (Corbett) should have been awarded a knighthood", although he refused to discuss the workings of the panel.
The entertainer's first honour came in 1978 when he was made an OBE alongside comedy partner Ronnie Barker, household favourites at the time for their sketch show The Two Ronnies.
Corbett was made a CBE in 2012, and the knighthood some felt he also deserved eluded him.