Bush made the remarks to more than 2,500 people Wednesday at the Lancaster Chamber of Commerce & Industry's annual dinner.
The 43rd president was by turns serious and humorous as he spoke about the defining decisions of his presidency.
Bush defended his authorization of enhanced interrogation techniques. He also defended the $700 billion financial bailout plan of 2008.
Bush left office in January 2009. He has kept a low profile since returning to his home in Texas, working on a memoir and appearing occasionally at speeches.