Just hours after he returned home to Massachusetts from a North Carolina hospital where part of his brain tumor was removed, Kennedy and his wife were out sailing in the waters off Cape Cod.
It's the same routine he followed last month after being released from a Boston hospital following his diagnosis.
Kennedy's office says he will continue to recuperate at home before starting the next phase of his treatment. The surgery a week ago was aimed at improving the success of chemotherapy and radiation.
His son, Congressman Patrick Kennedy, says he plans to have dinner with him tonight.
As for the benefits of being at home, Patrick Kennedy says it "always makes him feel great being near the ocean."
Kennedy left the hospital Monday morning and arrived at his family's compound in Hyannis Port on Cape Cod just before noon.
Kennedy told reporters waiting outside his home, "It's good to be home, good to be here."
The Massachusetts Democrat was diagnosed last month with a malignant glioma, a lethal type of brain tumor, after having a seizure at his Cape Cod home. A malignant glioma is one of the worst kinds of brain cancer, and malignant gliomas are diagnosed in about 9,000 Americans a year.
Kennedy, 76, underwent the risky, 3½-hour surgery last Monday to remove as much of the tumor as possible, a procedure aimed at improving the success of chemotherapy and radiation. His surgeon at Duke, Dr. Allan Friedman, said Monday that Kennedy "is making an excellent recovery."
"He will continue his recuperation at home in Massachusetts under the supervision of the very capable doctors at the Massachusetts General Hospital," Friedman said in a statement.
Kennedy's son, Rep. Patrick Kennedy, D-R.I., told the Providence Journal on Sunday that his father's surgery "went better than anyone expected." He said his father is looking forward to returning to the Senate and working with Democratic presidential nominee Barack Obama on universal health care legislation should the Illinois senator win the White House.
"That is what he is talking and thinking about," Kennedy said. "It adds a great deal of poignancy to his recovery. But that's how he sees it - he has to recover so he can get health care for the millions of people who don't have access to the care that we do."
Kennedy told the newspaper that his father wants to begin writing the legislation this year so it would be ready if Obama was victorious.
Kennedy's family and doctors have released few details about the particular type of tumor, which plays a key role in determining his survival odds. Some cancer specialists have said Kennedy appears to have a glioblastoma multiforme - a serious and tough-to-remove type of tumor - because other kinds are more common in younger people.
Doctors familiar with the type of surgery have said it almost never leads to a cure, but radiation or chemotherapy treatments have a better chance of success because there's less tumor to fight.
"The senator and his wife Vicki are wonderful people, and I hope you will join me in wishing them the best as they continue their difficult journey to fight this disease," Friedman said. "Their courageous and positive attitude is a lesson for us all."