Cook, who guided his side to a 3-1 retention of The Ashes in the summer, said that there is a lot to do both on and off the pitch which starts to drain energy.
"You do find it more tiring," he told Sky Sports News. "You get tested every single day and you don't quite know where you'll be tested from.
"Eventually that does wear at you. It's how you manage that, and how you try to put in place things that can help you.
"As a captain, Andrew Strauss was an outstanding bloke, and it's been quite hard to follow in his footsteps because of how respected he was. But I'd say we're slightly different in the way we handle the dressing room, perhaps because I'm slightly younger."
The first Test in the Ashes tour of Australia begins on November 21 at the Gabba, Melbourne.