Former President Jimmy Carter is celebrating his 95th birthday on Tuesday, October 1, solidifying his spot as the longest living president in United States history.

The 39th president, who's made a mark in his post-White House years as a human rights activist, author, professor, and church Sunday School teacher, is sharing the celebration with the public by offering a discounted admission fee to his presidential library. The Jimmy Carter Presidential Library in Atlanta announced the admission price on Tuesday would be just 95 cents — one penny for every year Mr. Carter has been alive.

Today’s the day! Celebrate President Carter’s 95th by visiting us for only 95 cents! See our #GeorgiaOnMyScreen film & TV exhibit, watch “Smokey & the Bandit,” enter our “S&TB” costume contest! We’re open until 8pm! Kids 16 & under free! https://t.co/seQ6TLF7YE #Happy95thJimmy pic.twitter.com/buF2NDc5gF — Jimmy Carter Library (@CarterLibrary) October 1, 2019

Mr. Carter officially became the oldest living president in history earlier this year, when he surpassed former President George H.W. Bush at 94 years and 172 days old.

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It's been 38 years since Mr. Carter left office, and he's continued to work hard even in his retirement. In 2002, he became the only U.S. president to receive the Nobel Peace Prize for work done after his time in office.

He's written over 30 books and served as University Distinguished Professor at Emory University for more than three decades. He finally got tenure at the school at age 94 — 37 years after he began teaching there. Over the years, he's also been a leading force behind Habitat for Humanity, volunteering to build homes for people in need.

Mr. Carter has also battled through many health struggles. In 2015, he was diagnosed with melanoma that spread to his brain and liver. "I was prepared to go, but things turned out for the better," he told CBS News, after immunotherapy treatments beat back the cancer.

The former president also holds another important title: husband. He and his wife Rosalynn Carter have been married for more than 72 years.

Earlier this year, Mr. Carter broke his hip at his home when he fell while leaving to go turkey hunting. He subsequently had hip replacement surgery. But less than a month later, the tenacious 94-year-old was back to teaching Sunday school.