MEMPHIS, Tenn. (AP) — Jimmy Carter's August announcement that doctors had discovered tumors on his brain came with a promise: The former U.S. president would scale back his work schedule.

Months later, he sheepishly admits that hasn't happened. Carter, who celebrated his 91st birthday in October, told The Associated Press he has a good reason: He feels just fine.

Carter, speaking with the AP hours before participating in a home-building project organized by Habitat for Humanity in Memphis, Tennessee, said he'll continue receiving immune-boosting drugs to help his body seek out cancer cells after completing four rounds of treatment. It's too early for doctors to determine the drug's result since August, he said. He also received a targeted radiation treatment that month.

"I've reacted well to the treatments," he said. "I haven't been uncomfortable or ill after the treatments were over. So that part of it has been a relief to me and I think to the doctors. But the final result of how well the treatments are combating or controlling the cancer, we don't know yet."

Carter said he hasn't cut anything from his schedule at The Carter Center, the human rights organization he founded after leaving the White House. He is demurring on an election monitoring trip this month in Myanmar, but election observers will include his grandson and the center's new CEO, Jason Carter.

He's also taken on a mediation role in a dispute among Martin Luther King Jr.'s children and has continued to act as Habitat for Humanity's most prominent booster.

Carter and the Atlanta-based charity have been synonymous for more than 30 years. Carter's presidential museum in Atlanta even includes an exhibit featuring a pair of his work boots and a hammer once used in a contest on the Tonight Show.

He and his wife, Rosalynn, have volunteered a week of their time annually since 1984, events dubbed "Carter work projects" that draw thousands of volunteers and take months of planning. The streak seemed at risk in August when he revealed his illness and doubts about making a planned November build in a remote region of Nepal.

Ultimately, concerns about civil unrest in the region forced the trip's cancellation rather than Carter's health (his doctors had approved the trip). Carter said he was looking forward to the planned building strategy there, describing plans for walls woven of bamboo with the anticipation of a builder starting a new project.

"Back in August ... I didn't know if I would be physically able or if the doctors would let me go to Nepal, but they finally approved my going, and I was very happy and excited about that," Carter said. "To find out that we couldn't go because of civil disorder in Nepal was just a very serious blow to me and I presume to the other 2,500 people who were going to join us down there."

Instead, Carter joined some of those volunteers raising the walls of a new home north of downtown Memphis on Monday morning after donning a white hard hat and a tool belt stocked with hammer, measuring tape and a thick pencil. He also will announce plans to return to the city in August for a weeklong project.

Carter said he likes detail work, such as placing trim around doors and windows. It reminds Carter of the furniture pieces he makes in a workshop inside the couple's compound in his small hometown of Plains, Georgia. Carter said he tries to become "a regular worker" at Habitat sites, with breaks for media interviews on the organization. His work ethic on these sites has become part of Habitat lore, a reputation of which Carter seems aware.

"While I'm working, I don't want anybody to bother me," he said, smiling. "I don't want other volunteers to be coming and taking photographs because they're not working and I'm not working when they're taking my photograph."

Next August, volunteers plan to build 21 homes in a Memphis neighborhood. The organization also plans to complete other home repairs and landscaping, along with home repairs or modifications for low-income seniors living around the area.

As for Carter, his favorite moment remains handing the keys and a Bible to home recipients, who along with volunteers are often moved to tears.

"As a matter of fact," he said, "I get maybe a little more emotional the older I get."