British World War II veteran Captain Tom Moore, 99, poses doing a lap of his garden in the village of Marston Moretaine, 50…
British World War II veteran Captain Tom Moore, 99, walks a lap of his garden in the village of Marston Moretaine, 50 miles north of London, April 16, 2020.

LONDON - A 99-year-old British World War II hero who set out to raise around $1,000 for health care workers battling COVID-19 has raised $16 million, and counting.

Captain Tom Moore of Bedford, 75 kilometers north of London, hoped to raise money by walking 100 times around his garden before his 100th birthday. By the time he completed the challenge Thursday, he had raised about $16 million, as the donations continued to pour in from around the world. More than 750,000 people have donated to his cause.

"It's unbelievable that people have been so kind to give that sort of money to the National Health Service," Moore told reporters Thursday. "Maybe I was responsible for starting it, but not deliberately. It was purely gratitude for what they've done for me."

WATCH: 99-Year-Old War Hero Raises Millions 

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Troops from the Yorkshire Regiment formed an honor guard for the final lap.

Moore will turn 100 on April 30. He wanted to raise funds for Britain's National Health Service (NHS) to thank what he called the "magnificent" staff who cared for him through cancer treatments and a broken hip.

Ellie Orton, chief executive of NHS Charities Together, to which the money will be donated, said the funds would be deployed immediately.

"It's going straight to the front line of the NHS. The staff, the volunteers, the patients, and supporting them."

Britain's Health Secretary Matt Hancock opened his daily press conference Wednesday with a tribute to Moore.

"Captain Tom, you're an inspiration to us all, and we thank you," Hancock said.

An NHS staff member wipes her eyes as she holds a sign to thank British veteran Captain Tom Moore, who raised money for the health care workers battling COVID-19, at Aintree University Hospital in Liverpool, north-west England, April 16, 2020.

Moore served in India and Myanmar during World War II. Now, like most Britons, he is at home amid the lockdown. His survival tip: optimism.

"The thing is, remember tomorrow is a good day. Tomorrow you will maybe find everything will be much better than today," he said.

Moore tweeted Thursday that he would keep walking as long as people continued to donate money.

His fundraising shows no sign of slowing down. Pledges totaling several million dollars came in Thursday as news of his accomplishment spread around the world.