Only a week after announcing that cancer was found in his body after a surgery for liver cancer, Former U.S. President Jimmy Carter said he would be starting radiation treatment on Thursday for brain cancer.

Carter explained at a news conference, both calmly and while in good spirits, that he will be receiving radiation every three weeks. The treatment is targeted at four “very small spots” of melanoma on his brain, he said.

Carter, 90, was president of the United States between 1977 and 1981. During, and continuing after his presidency, he became an active humanitarian and won the Nobel Peace Prize in 2002. During his time in the White House, his term was molded by national economic struggles and the Iran hostage crisis, according to Reuters.

He was asked during the press conference if he had any regrets in life. He admitted that he wished he had sent in one more helicopter in the failed attempt to rescue the Iran hostages. He added that it would not have only saved lives, but it could have set him up to be re-elected in one more effort as president.

In the 1980 presidential race, Republican Ronald Reagan defeated Democrat Carter.

Instead of having his medical news spread by spokespeople or through newspapers, Carter personally chose to share the news about his illness to the media directly. The news conference was held at the nonprofit Carter Center in Atlanta, where he showed up wearing blue jeans, in smiles.

“I am perfectly at ease with whatever comes,” Carter said, noting his deep Christian faith. “This is in the hands of God.”

He also added that he was far from anger about his situation, “I am ready for anything and looking forward to a new adventure,” Carter added.

During his surgery just a week ago, doctors removed one tenth of his liver, which in turn, through a biopsy, revealed that a form of skin cancer started elsewhere in his body, and then spread to his liver. Then, shortly after, doctors found the spots of melanoma on his brain.