But in the back of his mind was a nagging doubt about the year he was born, so the North Otago man ordered a birth certificate to double-check.
This showed he was indeed born in 1915, but to his amazement his birthday was July 20, a day earlier than he had believed.
The Waynestown resident, who turns 100 on Monday, has been celebrating his birthday on the wrong day all his life after his mother told him he was born on July 21.
And his birthday will be one to remember for more than one reason: it will be marked in Dunedin Hospital, where he has been for the past 12 days after he fell, breaking his hip.
Mr Smith was walking his Pekingese, Kelly, when she got a fright and bolted, wrapping her leash around his leg and tripping him over.
He planned to share a birthday lunch with 12 friends, and eat cooked Bluff oysters, he said.
''I love them.''
Once recovered, he would return home where he lived with his dog and hens.
His wife, Elsie, died 12 years ago, and his only child, Bill, died in a fishing accident aged 17.
Mr Smith said he had no secret about living a long life, but the former baker kept active in his retirement, building and renovating houses, gardening, making furniture, playing the accordion and piano, and reciting poetry.
He cooked hearty meals every night and baked for the Waynestown pensioners, serving his specialties of Shrewsbury and Belgian biscuits, shortbread and fruitcake.
''Just the easy ones; nothing flash.''
