Andrew Clark, 51, from Boston, Lincolnshire, said he was taking early retirement after discovering the winning ticket tucked in the visor of his Peugeot Expert van.
He made a claim for the prize - the 12th biggest win ever in the UK - last week, Camelot said.
Mr Clark, who was urged to check his stash by his partner, said: “Trisha kept telling me to check the tickets, and her niece Louise, who I was building an extension for, was also in on it once she’d heard about the unclaimed prize in the news.
“It was something of a standing joke that I had all these tickets while there was a local prize outstanding, so for weeks they were on at me to check.”
The ticket was bought from Eastwood Road Post Office in Boston.
Self-employed Mr Clark revealed himself as the winner at a press conference in Grantham on Friday morning.
Referring to himself as “the man who nearly lost £76 million”, he said he realised he was the mystery winner after he “finally gave in” and began working his way through his stash of tickets one evening.
He and his partner, Trisha Fairhurst, 51, have already bought a new home and two cars but say “the best thing about the win is how we can help all our family”.
The grandfather-of-three said: “It almost feels like some magical Christmas story, the man who nearly lost £76 million! For all our family, I’m very pleased that Trisha and Louise nagged me to check those tickets!
“This Christmas is going to be a quiet affair, but next year will be a different story. Trisha and I have this vision of hiring a big lodge or hotel so that the whole family can get together and swap stories about how they’ve spent their share over the past 12 months.
“This win isn’t just about Christmas magic, it’s about creating a lifetime of magical moments for all those around us.”