The colorful and complicated 39-year-old struggled "physically and mentally", losing 20 pounds off his already beanpole frame.
"Last year was one of the lowest points in my life," he told reporters. "It was a scary time."
But victory in Sunday's World Golf Championships Dell Match Play helped remind Watson of his unique talent as he joined only four other players to have won multiple majors and multiple WGC events, the second most prestigious group of tournaments.
The others are Tiger Woods, Phil Mickelson, Rory McIlroy and Ernie Els.
Watson's dominant win against Kevin Kisner set him up as one of the favorites at Augusta next week, something the lanky left-hander could barely dream about growing up in Bagdad, Florida.
All he ever wanted was to make the PGA Tour. Then he wanted to win an event. His next goal was 10 titles (he once said he'd quit when he got to 10). He's now on 11, with two majors.
"It's overwhelming," said Watson, who broke into his customary tears as he hugged his mother Molly on the final green in Austin, Texas.
"I can't make that into a real story. I should write a book, it would be a phenomenal book."
'Mind run wild'
Watson's unspecified medical condition affected his motivation and ability to hit the shots he saw in his vivid and creative imagination -- what he dubbed "Bubba golf" when he won the Masters for the first time in 2012.
The entirely self-taught big hitter questioned whether he wanted to miss out on so much family time -- he has two adopted children with wife Angie -- "battling trying to make cuts on the PGA Tour."
The alternative was to return to relative obscurity in Pensacola, Florida, running his Chevy car dealership, a candy shop named "Bubba's Sweet Spot," the Blue Wahoos Double A baseball team and a 256-apartment complex. There's also a clothing brand in the pipeline.
He spent a lot of time soul-searching, talking to Angie, his caddie Ted Scott and the team around him. He came to realize that shaping golf shots and trying to win tournaments was what made him happy.
"I want to let my mind run wild on the golf course," he said. "That was my passion. The other things are my passion, but right now I still feel like I have the ability to play golf."
Plus, he didn't much fancy the alternative.
"Going to an office every day didn't feel like it would be fun," he said.
As Watson continued to figure out "what drives me as a person," his health began to improve. His victory at the Genesis Open at Riviera in February was his first win for two years.
Heading to the Masters, which he describes as the "greatest sporting event in golf history," he is determined to keep his head down — "look like a zombie" -- and not get distracted by the hype surrounding him.
But while collecting trophies or green jackets ("I never felt a coat feel so good") is fun, Watson insists the best honor in his career is being able to help with charitable causes.
Last year he donated $1.6 million to the Studer Family Children's Hospital at Sacred Heart in Pensacola.
"Me donating money to the Children's Hospital, that's the biggest trophy I've ever been a part of," Watson said.
"When I'm no longer here, there's going to be people being helped, kids being helped, families being helped. The Ronald McDonald house that's attached to the hospital, we've been a part of that, seen some amazing stuff happen there.
"So when I look back at my career, it's the stuff outside of golf. This check this week will help me do a lot of good throughout different communities."
Thomas distracted by No.1
As Watson climbed back up to 21st in the world rankings (he's been as high as four), his semifinal win against Justin Thomas kept his fellow American from a maiden stint as world No.1.
An appearance in the final would have catapulted Thomas over Dustin Johnson, but the 24-year-old admitted he became distracted by the prospect of topping the rankings.
"I haven't had such a hard time not thinking about something so much," Thomas told reporters.
"And that really sucked. I couldn't stop thinking about it, to be perfectly honest."
One win, two cars
Sponsored by a car company, it's perhaps no surprise South Korea's Eun-hee Ji collected some new wheels as part of her prize for winning the LPGA Tour's Kia Classic in California.
But Ji's seven-iron ace at the 166-yard 14th hole, which took her three shots clear of Cristie Kerr to set up the win, also earned her another of the sponsor's motors sitting next to the green.
The 31-year-old Ji, a former US Women's Open champion, is ranked fourth in the world and has won more than $5.8 million in career prize money on the women's LPGA Tour.