(CNN) Captain Tom Moore, the now famous 99-year-old British war veteran who has raised more than £19 million ($23.7 million) for the UK's National Health Service (NHS) by walking 100 laps of his garden, has said he is "absolutely overwhelmed" by the sum he has been able to raise.
Moore, who will turn 100 later this month, began a JustGiving fundraiser on April 8, initially hoping to raise £1,000 for NHS Charities Together, which raises funds for UK hospitals, including for staff, volunteers and patients affected by the coronavirus crisis.
He completed the challenge on Thursday, after walking 10 laps of his garden each day, aided by a walking frame. He told CNN he never anticipated being able to raise such a sum.
"I'm absolutely overwhelmed by this sum of money -- and when you transfer those into American dollars it's even bigger. We really never, ever for a minute thought we would get to this sort of money. We started off with a little modest figure," he told CNN's Hala Gorani on the "Connect The World" show on Friday.
Born in Yorkshire, northern England, Moore trained as a civil engineer before being enlisted in the British Army during World War II, where he served in India, Indonesia and Britain. He later became the managing director of a concrete manufacturer.
Following the death of his wife in 2006, Moore moved in with his daughter, son-in-law and two grandchildren in Bedfordshire, southeast England, where he still lives.
Asked why he believed his fundraiser had struck a chord with so many people, he said: "I think because our National Health Service is good -- they do so good for me -- I had a broken hip and I had cancer and they treated me magnificently.
"I think people realize that...everyone, wherever they are, gets equally treated, just as well, with the same efficiency and kindness that we get from our nurses and doctors -- who, after all, at the moment are on the firing line (of the coronavirus crisis)."
There are growing calls for Moore to be honored for his service to the UK. More than 500,000 people have signed an online petition calling on the government to give him a knighthood.
A spokeswoman for Number 10 Downing Street said in a statement that Prime Minister Boris Johnson will look at ways to recognize Moore's efforts.
"Tom has captured the heart of the nation with his heroic efforts and raised an incredible amount of money for hard working NHS staff," the spokeswoman said in the statement.
"He has embodied the spirit of the whole country in doing their bit for the battle against coronavirus to support the NHS and save lives. From his military contributions to his support for NHS staff, Tom has demonstrated a lifetime of bravery and compassion.
"The PM will certainly be looking at ways to recognize Tom for his heroic efforts."
Tributes and thanks, meanwhile, have poured in from around the world for his fundraising efforts.
UK Health Secretary Matt Hancock said Thursday he was "inspired" by Moore's efforts. On Friday, Prince William, the Duke of Cambridge, said in an interview with BBC Breakfast that Moore was a "fundraising machine."
"It's wonderful that everyone has been inspired by his story and his determination," he said. "I think he's a one-man fundraising machine and god knows what the final total will be but good on him, I hope he keeps going."
Asked what he made of being called a hero, Moore thanked people for "their kind remarks" and said: "Let me assure you -- eventually, we shall all get through it, and all will be well in the end."