Haye will rematch Tony Bellew on May 5, live on Sky Sports Box Office, and believes defeat in their first meeting was partly caused by complacency from his previous fights.
He needed less than a combined three rounds to knock out Mark de Mori and Arnold Gjergjaj having come out of retirement.
“The Dereck Chisora fight was my last competitive boxing match. Outside of that, in the two comeback fights, I didn’t get punched once. It was just me beating someone up,” Haye told Sky Sports.
“I overestimated how good I was. I thought that I was as good as I was in 2012.
“You can’t just take a break, come back, and expect to be just as good. You need to work your way back up.”
Haye took on Bellew last March, four-and-a-half years after beating Chisora, and suffered a late stoppage having injured his Achilles.
Now aged 37, he insists that he did not take Bellew, who was making his heavyweight debut, lightly.
“I overestimated myself, I’m not sure that I underestimated him,” Haye claimed.
He has since enlisted the help of trainer Ismael Salas, who will be in his corner for the first time in the Bellew rematch.
The winner of next weekend’s rematch has been targeted by Joseph Parker, who used Haye’s gym to prepare for his unification fight against Anthony Joshua last month.
“Joseph Parker himself and our team would back him against almost anyone, and certainly would back him against the winner of Bellew-Haye,” said the former world champion’s promoter David Higgins.
“For those British contenders, respect to the one that does step up to Parker, because I think, despite Parker not quite getting the win, he gained a lot of respect, and is the first man to take Joshua the distance.”