The lively Dunedin couple, who are "at the thick end of [their] 80s", married in 1943 and say they have enjoyed caring for one another since.
The pair met at a party in Dunedin in the late 1930s, soon after Mrs Watts moved to the area from Napier with family.
When World War 2 began, Mr Watts volunteered for the infantry before transferring to a radar operations unit.
His father served in World War 1, and warned him of being in the thick of a war of attrition.
"I thought 'right, I'm not going to be a footslogger'," he said.
He was granted special leave to return from service as a radar operator in the Pacific to marry Iris in 1943.
After the war, the couple settled in Dunedin and raised four sons.
"I couldn't believe it when a son told me they were turning 63 - I don't feel 60 myself," Mrs Watts said yesterday.
Although she was often at the copper washing up to 40 shirts each weekend, she was an active sportswoman and took many wickets for the Grange Cricket Club, played netball and had a keen interest in dance.
The couple later owned Watts Food Store, managed hotels and were custodians at Kaikorai Valley College before retirement to Green Island.
"You realise the honeymoon does not last forever. But marriage is a commitment you either make, or you don't. We have really loved and cared for one another for all these years," Mr Watts said.
Mrs Watts said Bill was a "fantastic husband" and was moved to tears at her recent birthday celebrations when he recited a poem describing his enjoyment of their life together.
Mr Watts said there was no "secret" to their long marriage; they enjoyed each other's company and had a strong commitment to family life, which saw them turn to each other in times of adversity.
Mrs Watts has suffered ill health following a stroke in the 1980s, and her husband has cared for her at home for almost 20 years.
"They wanted to keep Iris at the hospital [after one episode], but I thought `I think we should try and prove a point here'," Mr Watts said.
The couple will celebrate their anniversary with family in Dunedin today.
