Koepka finished the Masters in a disappointing share of 45th place and was never really in contention a year after tying for second at Augusta National.
The five-time major champion, who lives and breathes golf's blue-riband events, then apologised to his team for his performance and they swiftly put him through gruelling workouts in a bid hopefully to avoid further letdowns.
"I mean, I'm not looking for the punishment workout. I just get told," Koepka said on Wednesday during his eve-of-tournament press conference.
"It sucks. It's not a lot of fun. A lot more running. Very up-tempo, no rest.
"I think I had like four or five days in a row of just -- I turned white, I wanted to throw up in a few of them. But yeah, got through it."
The workouts paid off as Koepka's game seems to be coming into form -- he won the recent LIV Golf event in Singapore -- and now turns his attention to a Valhalla Golf Club layout in Louisville, Kentucky, that should play to his strengths.
"It's a long golf course. So you've got to be able to hit the ball far," Koepka said about the 7609-yard layout.
"The fairways ... are generous. I don't think they are overly generous, but you can take advantage of them. The rough is thick. If you're going to miss fairways, you're going to be in trouble."
Koepka has firmly established himself as a PGA Championship specialist and his eight top-15 finishes over the last 10 editions of the major include a trio of wins.
Much of the build-up to this year's PGA Championship has centred on the fact that world No.1 Scottie Scheffler, No.2 Rory McIlroy and Koepka each have a win in their most recent start.
But Koepka, who does not get to put his game up against Scheffler and McIlroy outside of the majors given he is a LIV Golf player, said he is not too focused on that angle.
"I'm just looking forward to a major championship. Gets my excitement going. Something I look forward to all year," said Koepka, who is looking to become the event's first repeat winner since he successfully defended his title in 2019.
"So yeah, look, I always enjoy competing against these guys, and anytime you get the best, it's always good, and you just want them to play their best, too. You want to go out and win it."
