At 100 years old, Bob Penney likes to spend his days relaxing, listening to audiobooks at the East Chop home he bought in 1952. His favorite, Winds of War by Herman Wouk, reminds him of his Navy days during World War II.

He said he feels “just like any average 100-year-old man. I think other people are really more interested than I am.”

But his quiet days were interrupted on August 21, his 100th birthday, as about 40 people visited to celebrate and eat cake. And for days on either end, family and friends visited the Island to spend time with Mr. Penney.

The fanfare didn’t phase him much. “I don’t get excited much anymore,” he said.

But one moment did stand out: receiving a letter from the President of the United States.

“It is a privilege to wish you a happy 100th birthday and to thank you for your inspiring service in the United States Navy,” read the letter, signed by President Joe Biden.

“Pretty exciting, I guess,” Ms. Penney said. “He never wrote to me before.”

Mr. Penney spent his childhood working at his father’s Oak Bluffs restaurant, called the Dinette, and was the third-ever employee at DaRosa’s Print Shop on Circuit avenue.

“I’m still waiting on the pension from that one,” he said.

Bob Penney raises the flag with help from Heidi Dahlberg. — Jeanna Shepard

His favorite jobs, though, were being a milkman and a post office clerk. Both jobs started early and finished early, leaving time for Mr. Penney to have fun on summer afternoons. He was always out on the water on rented sailboats as a kid, and he bought his own when he retired. He remembers a different Island in those days — one with longer winters, and cheaper food and gas.

In the colder months, the harbor or the pond would freeze over and New York avenue would be closed for a few hours when it snowed so kids could sled. He would skate on the pond holding onto a long pole so he could escape the water if the ice cracked.

He graduated from high school “in the top 10,” he likes to say.

His friend Heidi Dahlberg, who often stays over to help out, added with a laugh that were only 10 students in his graduating class.

He moved off-Island after high school to attend Tufts University, but his freshman year was interrupted in 1941 by the attack on Peal Harbor, and he joined the Navy. His service was all stateside but the experience stuck with him — his favorite book and the model planes on his coffee table offer opportunities to reminisce.

“Nobody shot at me, so that was pretty good,” Mr. Penney said about the war. “They called us the ‘hurricane hunters’ but luckily I never found one.”

He learned to fly multi-engine planes, hoping to become a commercial pilot after the war. But after training and flying around the United States, he resigned from the armed forces when there was talk of sending him to Alaska for three years.

“I decided it was time to get out,” he said.

He returned to Tufts to finish his degree and applied to commercial airlines to become a pilot. After never hearing back, he attended Boston University School of Law with his tuition paid for by the G.I. Bill. He spent the next 36 years working as a lawyer for Liberty Mutual Insurance.

His proudest accomplishment is briefly appearing before the United States Supreme Court. He didn’t want to go into any details of the class action suit, but then joked, “Nobody else is alive who took part in it, so I could say whatever I want.”

After retiring as a vice president and senior counsel at the insurance company, he returned to the Vineyard to live fulltime at Penney’s Landing, the name he gave his East Chop home, made official with custom doormats and a sign on the porch.

Mr. Penney said he remembers when a house in the Camp Ground cost only $3,000 fully furnished, and when a full roast beef dinner, appetizer and dessert included cost 60 cents at the Dinette. He recalls when gas on the Island was 25 cents a gallon or you could buy six gallons for a dollar, he said.

When asked what the secret was for living a full century he didn’t hesitate. “Not getting shot by a jealous husband,” he said.

Ms. Dahlberg laughed and offered that maybe he didn’t want a reporter putting that comment in the paper.

“You can if you want to,” Mr. Penney responded with a big belly laugh. “What do I care?”