Slovenia-born Bedene, who plays world number one Novak Djokovic in the third round of the French Open on Saturday, credits his work with Martin Skinner as the platform for his recent success.
"I was really unfit when I started to play grand slams," said Bedene, 26.
"Whenever I played a fourth set I was just losing them quite easily."
He added: "I remember once at the US Open, I lost 6-0 and I was struggling. I really wanted to improve on that.
"It obviously helps not only in the fifth set but also in the other tournaments."
Bedene is buoyed by Thursday's five-set, second-round victory against Pablo Carreno Busta when he recovered from squandering a two-set lead to advance at Roland Garros.
However, he lost his only other meeting with Djokovic in straight sets at the Australian Open in 2015.
He is hoping his experience of winning 16 Challenger and Futures events will stand him in good stead for the game, which is last on the main court.
"I love big crowds," he said. "I won a lot of Italian Challengers, and every time you play the final there are 1,000, 2,000 people, which is a lot for Challengers.
"So I did learn a few things. I know this stadium is bigger, but still you have to come from somewhere."
Djokovic has not hit top form yet and was given a tough test by qualifier Steve Darcis in round two, although he is still to drop a set.
The Serb is expecting more of the same against Bedene, who is being coached at Roland Garros by Britain's Davis Cup captain Leon Smith.
"He's very talented, with a very quick motion for a first serve," said Djokovic. "So I'm expecting a tough one. I know he doesn't have anything to lose."
British number two Aljaz Bedene says he had to employ a strength and conditioning coach to specifically prepare him for grand slam tennis.