The 90 year old went public with his health crisis on Wednesday (12Aug15) after undergoing surgery to remove a small mass in his liver earlier this month (Aug15).

He held a press conference at his Carter Center charity base in Atlanta, Georgia on Thursday (20Aug15) to discuss the news, and he revealed doctors have found "very small spots" on his brain.

Carter has vowed to "cut back fairly dramatically" on his activities, but admits he is "perfectly at ease with whatever comes" even though he recently feared he "had just a few weeks left," adding, "I've had a wonderful life. I've had thousands of friends... Living to be 91 years old in October, so I'm thankful and hopeful."

The former leader also revealed he has been inundated with phone calls from some of the most high-profile names in U.S. politics: "Both former President Bush (sic) called me... I appreciated that very much... President Obama called... Bill Clinton called... Hillary Clinton called... First time they've called me in a long time."