"You know, not having weapons of mass destruction was a significant disappointment," he said, referring to the discovery that Bush's rationale for the Iraq War didn't exist. "I don't know if you want to call those mistakes or not, but they were things [that] didn't go according to plan."
On the domestic front, the president also assessed criticism about the government's response to Hurricane Katrina, becoming defensive when again challenged about whether the administration had acted appropriately.
"Could things have been done better? Absolutely," Bush said. "But when I hear people say the federal response was slow, then what are they going to say to those chopper drivers or the 30,000 that got pulled off the roofs?"
The president who was noted for long vacations at his Crawford, Texas ranch said the job of being president followed him every where. Bush said he got national security briefings every day but Sunday, and it was impossible to escape the job.
"There's not a moment where you don't think about being president. Unless you're riding mountain bikes as hard as you possibly can, trying to forget for the moment," he said.
But now he is "getting off the stage," he said and didn't know what he will be doing after moving out of the White House next Tuesday.
"I'm a Type A personality…I just can't envision myself, you know, the big straw hat and a Hawaiian shirt sitting on some beach, particularly since I quit drinking," Bush said.
ABC News' Gary Langer contributed to this report.