Padraig Harrington admitted his relief after getting a second chance to clinch the Open title in a play-off against Sergio Garcia at Carnoustie.
Harrington won the Open play-off by one stroke
"I think if I'd lost it would have been very hard to take," said the Irishman, who had reached the 18th a shot clear but then found water to double-bogey.
"If Sergio had parred the last and I'd lost, I think I would have struggled to come back and be a competitive golfer.
"I would have struggled in the future," an emotional Harrington told BBC Sport.
"But I didn't allow myself to get down about taking six at the last.
"I convinced myself all along I was going to win and that if it was a play-off, I would do the business."
Instead, Harrington has become the first European to win a major since Paul Lawrie triumphed in 1999, also at Carnoustie, and the first Irishman to win the Open for 60 years.
He added: "I'm sure there's a hell of a party (in Ireland) now and I know I don't have anything to do for two-and-a-half days so I'm going to party on."
CAREER OF AN OPEN CHAMPION
1971: Born on 31 August
1995: Wins Spanish Open a year after turning pro
1999: Makes Ryder Cup debut
2000: Has five-shot lead going into final round of B&H International but is disqualified after not signing his scorecard
2001: Wins season-ending Volvo Masters
2002: Beats Tiger Woods head-to-head in Target Challenge
2005: Wins twice on US Tour
2006: Wins European Order of Merit; Plays in 4th Ryder Cup
The 35-year-old, who is coached by former Ryder Cup captain Sam Torrance's father Bob, admitted that it had been "a long road" since he turned professional at the age of 21.
"I decided I would turn pro because the guys I was able to beat as an amateur were turning pro," he said.
"I thought I would have a great life and if I did well maybe I'd make a comfortable living on the tour."
But after struggling in the US, he realised his game was not good enough to compete at the highest level and he resolved to knuckle down, becoming one of the hardest practising professionals in the game.
Harrington has endured his fair share of bad luck with a record 30 runner's-up finishes - to go with his 14 titles - on the tour.
The qualified accountant has also gone close before at majors with five fifth-place finishes, the most recent at the US Open at Winged Foot last year, when he finished two behind Geoff Ogilvy after three closing bogeys.
That was the second time he has stood on the final tee still in with a chance of victory.
Four years ago at Muirfield, a closing bogey left him one shot out of the play-off when Ernie Els beat Thomas Levet, Stuart Appleby and Steve Elkington.
But the work ethic of the teetotal Dubliner has finally paid off with an Open victory, with Harrington determined to add to his tally now that he has broken his major duck.
"My goal was always to win more than one major," he said.