Speaking to talkSPORT, Cooper promised that more of the same is to come throughout the season.
"From day one when the manager came in, he said we're going to take risks and we're going to be offensive," the defender said. "He doesn't want his teams to defend too much and he's adamant we're going to take risks, and that's the way we're going to play.
"It's going to be exciting. The lads have really bought into his philosophy and what he wants us to do and try. It took some getting used to – we were running three and four sessions a day for five or weeks over the summer – but now you can see in training the performances levels have gone up and the fitness levels are really high.
"The lads are saying it's the fittest they've ever felt, so long may that continue."
Leeds face Frank Lampard's Derby County in their next test on Saturday.