Former president George W. Bush said Thursday morning that he isn't going to spend time trying to improve his presidential image and hit back against critics, adding that he believes that history will vindicate him.

"I have no desire to spend my post-presidency trying to enhance my standing," Bush said in an interview with "CBS This Morning." Bush has been conducting a media blitz in advance of the dedication Thursday of his presidential library at Southern Methodist University in Dallas.

"Historians will eventually sort out the good and the bad" of every president, said Bush, who added, "I have got this great faith in history."

Bush said his father, former president George H.W. Bush, "can't walk very well" but has "a strong desire to live." The elder Bush was released from a Houston hospital earlier this year. He had been undergoing treatment for a cough and fever.

On his controversial decision to invade Iraq, Bush said it is "hard to tell" whether the invasion would have happened had he realized the country did not have weapons of mass destruction.

Bush has taken up painting since leaving office, a hobby he said relaxes him and gives him a "whole new way of looking at the world." The former president said he spends about two or three hours a day painting.

On the topic of immigration reform -- an issue Bush tried, unsuccessfully, to tackle as president -- the former president said he is impressed by the work lawmakers are currently doing to overhaul the nation's immigration laws, and is hopeful they can shepherd a reform bill to passage. "I hope it happens because it's the right thing to do," he said.