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."

The comments were made in a statement the day after the BBC reported workers at Scotland's largest container port are set to go on strike on Tuesday in a row over rotas and pay.
The spokeswoman insisted changes to shift patterns were needed to reflect the needs of customers.
But the Unite union has said the new rotas amount to a "de facto pay cut".
A spokesman for the Port of Grangemouth said: "The strike action proposed by Unite the union is unjustified.
"We are proposing alterations to shift patterns in response to the changing needs of our customers, whose vessels call at the port seven days a week.
"Our staff and their union accepted the need for such flexibility, and that shift patterns may require to change in the future, when this element of their employment contracts was agreed in 2011.
She added: "We have decided to close the port's quayside container operations from midnight on Monday 14th March. All other operations at the port will remain open.
"We sincerely hope that our staff, and their union, will cancel this strike and work with us to implement the changes necessary to enable us to meet the changing demands of our customers."
The union Unite has said all but two of 75 "operatives" based at the Port of Grangemouth voted for the action in a ballot.
The workers include crane drivers and loaders.
It is understood that about 20 engineers who are also based at the site are not involved in the action, which is due to start at 00:01 on Tuesday.
Unite said the action had been called after port owner Forth Ports announced changes to shifts.
Grangemouth handles more than 150,000 containers annually, with daily sailings to Rotterdam, Antwerp, Felixstowe and Hamburg.
British number two Aljaz Bedene says he had to employ a strength and conditioning coach to specifically prepare him for grand slam tennis.
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A spokeswoman for Forth Ports has called the planned Grangemouth strike "unjustified".