Brooks Koepka admitted he did not even dare to dream about winning two majors in 2018 while he was sidelined by injury earlier this year.
Koepka was out of action for four months after being forced to undergo wrist surgery following the Sentry Tournament of Champions in the first week in January, and his long recovery process prevented him from competing at the Masters in April.
The 28-year-old returned to action at the Wells Fargo Championship in early May and, after suffering a scare at The Players Championship when he aggravated the problem on the practice range, Koepka became the first man since Curtis Strange in 1989 to successfully defend the US Open title at Shinnecock Hills.
Koepka struggled to get into contention in The Open at Carnoustie, but he collected his third major title in his last six starts with an impressive two-shot victory over a rejuvenated Tiger Woods after a thrilling final round of the PGA Championship.
He matched his third-round 66 to secure the Wanamaker Trophy at the Bellerive Country Club, and he said: "It's incredible. To think where I was four months ago, I didn't really even dream about this. And to come out here and play as well as we did, it's really incredible.
"I struck it so well at Firestone last week, I just wasn't putting well so that's all we focused on when we got here. We just needed to hit the ball well, and Claude (Harmon, Koepka's coach) didn't say one word to me this week - I was hitting it that good.
"He just stood behind me and was like, 'yup, that's perfect'. And we just worked on some putting and that was it and making sure my head stayed still. And to come out here and play as well as we did was really, I can't even put into words how well I played and I'm so excited for myself, my caddie and my team.
"When I look at what I've done in the past two months, I was sitting on my couch watching the Masters, and to think I would do this? I would have laughed at you and told you there was no way, no chance, and to do it is really incredible.
"My doctors, physios, trainers, everybody did an unbelievable job even to get me back out on the golf course, and to do what I've done is very impressive. I can't even believe it."
Koepka was delighted with how he held his nerve down the stretch under huge pressure from Woods and playing-partner Adam Scott, with birdies at 15 and 16 proving decisive in the outcome.
"Obviously it was kind of the first time Tiger's been in contention and I've been in contention at the same time, so the fans definitely let you know what he was doing," he added.
"And I was playing with Scotty, so I knew what I was up against with him. And Scotty played unbelievably well and so did Tiger. They definitely made me question it there for a bit or think about it, for sure."
Koepka jumped two clear of Scott when he followed his birdie at 15 with another at the tough 16th, where he drilled a stunning 247-yard long-iron to six feet, a shot he described as one of the best of his career.
"It's extremely gratifying, he added. "When you look at four and five to make two bogeys there, and I think I was tied for the lead at that point. Obviously, I had to get it going, so to birdie seven, eight and nine was kind of a big momentum shift for me.
"And especially with Tiger making that run, and then Scotty birdied 12 and 13, and it became a really tight race. But the shots I hit coming down the stretch were very good.
"We had a perfect number into 15, and then 16, I mean, I hit a laser right at the flag. That will probably go down as probably one of the best shots I've ever hit under pressure."