Now he is gearing himself up for another Major challenge.
"I got married to Laura, I have a kid on the way, so I guess my thinking has changed towards them rather than golf," said the 36-year-old Scot, who will allow his focus to switch to this week's US Open at Pinehurst. "My life has changed over the past year and it's now family first."
Flip the clock back to last June and Doak was preparing for another first: a maiden Major appearance in the US Open at Merion. It was always going to be an emotional ride. This was the storied venue upon which the great Ben Hogan marched triumphantly in the 1950 championship. Going there was particularly poignant given the special bond between Hogan and Doak's long-standing coach Bob Torrance.
Doak may have missed the cut at Merion but he left a lasting impression on the galleries. His white bunnet, the headwear of choice of barn-storming Ben, may have been originally adopted by Doak as a tribute to Brian Johnson, the flat-cap wearing frontman of raging rockers AC/DC, but it went down a storm with the whooping and hollering punters.
Merion was a memorable, if mind-mangling, experience for the Major rookie but it was all part of the learning process. Having earned a swift return to the US Open stage by coming through the international qualifier at Walton Heath a fortnight ago, Doak is adamant that lessons have been learned. He is not pitching up at Pinehurst just to make sartorial statements.
"I'll be a hundred times better prepared than last year," said Doak. "It was all very exciting with it being my first Major and it being Merion and the Hogan story and all that kind of stuff. It was too exciting for me to have done well. I'll pace myself better this time. I played four practice rounds last time and that doesn't work for me. I'll take it easier at Pinehurst. It will be quality rather than quantity."
As he hurtles through his 30s, Doak continues to flourish. He was always a naturally gifted golfer and won just about everything that was up for grabs on the domestic Tartan Tour. Moving up the perilous, slippery rungs of the professional ladder has not been easy but Doak's drive and determination have now got him to the point where he has established a firm foothold on the European Tour. A career-best cheque for a 12th-place finish in the BMW PGA Championship at Wentworth recently proved that he is increasingly comfortable in this rarefied air.
Majors are a different kettle of water-dwelling creatures, of course, but Doak is eager to embrace the challenges instead of being overawed by them. This is the level all golfers want to be competing at, after all, and the former Scottish PGA champion continues to harbour lofty ambitions.
"When I topped the Tartan Tour Order of Merit in 2005 I suppose tournaments like the US Open figured in my thoughts but it wasn't a clear vision; it was more a boy's dream to play in the Majors," he reflected. "At the end of the day I've made it to the US Open again through a regional qualifier but I want to get to the stage where I don't have to qualify that way for these things. Then it becomes real. It was a kind of fairy-tale thing last year when you were thinking you could go and maybe win. This time it's more business-minded.
"I'd be happy with a top 20 or 30 and anything else better would be fair enough. I'll definitely be playing it a different way. The last one, I was kind of gung-ho and went for flags, and realised it's not like that in Majors."
Pinehurst No 2, which last hosted the championship in 2005, will present an altogether different test to the usual US Open fare. The restoration of the course has led to the removal of the lush, wall-to-wall green grasses that carpeted the layout. In its place are wider fairways that spill into unmaintained edges with sand, pine straw and natural wiry grasses. There will be no gouge-out rough so typical of the war of attrition that is a US Open.
Whatever perils and pitfalls Pinehurst throws up, Doak will be ready for them. He will be keeping distinguished company this week but the Scot is relishing the prospect of being part of this glittering guest list.
"I'm now trying to beat my heroes instead of being in awe of them," said Doak, , who will be joined by compatriot Stephen Gallacher at Pinehurst. "I've met a lot of them and there's none of that now. It's a different mindset these days."
Doak's life continues to change.