(CNN)—In a remarkable press conference marked by grace and devoid of self-pity, former President Jimmy Carter said Thursday that four spots of cancer had spread to his brain. Read More

(CNN)—In a remarkable press conference marked by grace and devoid of self-pity, former President Jimmy Carter said Thursday that four spots of cancer had spread to his brain.

Carter, 90, said he initially thought he had only weeks to live when he first learned of the diagnosis. He’s now more optimistic, placing his fate in the hands of God. At the news conference in Atlanta where he sat alone before a bank of reporters and cameras, Carter said he would begin a course of radiation therapy on Thursday afternoon.

“I have had a wonderful life,” Carter said with the same unsparing honesty and meticulous detail that marked his presidency. “I’m ready for anything and I’m looking forward to new adventure,” Carter said, in the 40-minute appearance before the cameras, in which he frequently beamed his huge smile and never fell prey to emotion.

“It is in the hands of God, whom I worship.”

Carter, speaking slowly and softly and wearing a coat and tie with blue jeans, said he had been overwhelmed with phone calls of support — including outreach from Secretary of State John Kerry and former presidents George H. W. and George W. Bush, who called at once. Carter said he wasn’t in a lot of discomfort but had some shoulder pain.

Carter said in the immediate aftermath of the diagnosis, “I just thought I had a few weeks left (to live), but I was surprisingly at ease — much more so than my wife was.”

His devoted partner Rosalynn, the former First Lady, looked on, as Carter described her as the “pinnacle” of his life. “We’ve had 69 years together, still together,” Carter said.

The former president announced that he would cut back on the globetrotting personal diplomacy, peacemaking, election monitoring and pioneering public health work with which he has redefined the role of presidents once they leave office. He said his symptoms first appeared during a trip to Guyana earlier this year. On his return, doctors found a small tumor on his liver and diagnosed melanoma, which was later found to have spread to four spots on his brain.