Novak Djokovic says he doubted he would ever win another Grand Slam before ending a two-year drought by claiming his fourth Wimbledon title.
Djokovic, 31, won his 13th major by beating South African eighth seed Kevin Anderson in straight sets on Sunday.
The Serb struggled for form and fitness after his 2016 French Open win, falling out of the top 20 earlier this year.
"There were several moments where I was frustrated and questioning if I'd get back to the desired level," he said.
"But that makes this whole journey even more special for me.
"I'm really grateful to go through these mixed emotions and turbulence mentally. I'm human and we all have to go through that."
'I didn't expect to be in top shape'
Djokovic dominated the men's game earlier this decade, holding the number one ranking for 223 weeks and completing a career Grand Slam when he claimed the title at Roland Garros two years ago.
However, his form tailed off as he dealt with what he described as personal issues, before a persistent elbow injury also began to affect him.
He did not play the rest of the 2017 season after losing in the Wimbledon quarter-finals, opting to rest before returning at this year's Australian Open.
Still it gave him problems, particularly during his quarter-final defeat by Hyeon Chung, leading to surgery at the start of February.
He returned for the clay-court season but after losing to unseeded Italian Marco Cecchinato in the French Open quarter-finals claimed he might skip Wimbledon.
"I did not expect to be back in the top shape already here in Wimbledon so quickly," Djokovic said.
"If you asked me after Roland Garros, I would probably maybe doubt that.
"At the same time there is a part of me that always believes in my own abilities, believes in my own quality of tennis, what I possess.
"Whenever I come to the tournament and Grand Slam especially, I believe I can have a good opportunity to fight for the trophy."
Anderson still believes he can win a Slam
Anderson, 32, says he has a "lot of belief" he can reach another Grand Slam final, despite losing a showpiece in successive sets for the second time.
Victory over Djokovic would have made him the second oldest first-time Grand Slam champion in the Open Era.
Spain's Andres Gimeno was 34 years and 206 days when he won the 1972 French Open.
"I definitely believe I have the game to win these tournaments," said Anderson, who lost to Rafael Nadal in last year's US Open final.
"Even though it was a huge goal of mine, if you asked me this time a year ago, I don't think I could sit here and say I really believe that I can win a Grand Slam and a Masters Series and say it with the same self-belief and confidence that I can now.
"Obviously, that's by no means a sure thing whatsoever, but it's a big starting point.
"It's taken a long time to get to this point. I feel like I'm on a great path."