“There is a fountain of youth: it is your mind, your talents, the creativity you bring to your life and the lives of people you love. When you learn to tap this source, you will truly have defeated age.”– Sophia Loren

Age is just a number, and many remarkable things have been accomplished by people over 60. Here are just a few:

Peter Mark Roget was nearing his 70th birthday when he was forced to retire from the Royal Society, London’s esteemed collection of scientists, so that the younger generation could begin its work. Instead of resting on his laurels, though, Roget turned to a project that had interested him since the time he was a young man—a scientific ordering of language. Long compelled to make lists of similar words, he envisioned a book that would not define words, but group them according to a classification, such as “space” or “moral powers.” The first edition of Roget’s Thesaurus was published when Roget was 73, and he oversaw every update until he died at age 90. He had managed to create one of the most enduring reference materials in his retirement years.

Anna Mary Robertson Moses was better known to the world as Grandma Moses, a woman who didn’t begin to paint until the age of 76, when her hands became too crippled by arthritis to hold an embroidery needle. She found herself unable to sit around and do nothing, after a long life spent working on farms. Grandma Moses never had any formal art training. Indeed, she’d had very little formal education at all. But she painted every day, turning out more than a thousand paintings in 25 years. When an art collector passing through her town saw the paintings selling for a few dollars in a drug store, he bought them all and arranged for them to be shown at the Museum of Modern Art in New York City. Even with her newfound fame, her topics remained the same—nostalgic, colorful scenes of farm life, such as the first snow or a maple sugaring. When she died in 1961 at age 101, then-President John F. Kennedy released a statement praising her paintings for inspiring a nation, noting, “All Americans mourn her loss. “Governor of New York, Nelson Rockefeller had declared on her 101st birthday that there was “no more renowned artist in our entire country today.”

Laura Ingalls Wilder’s best-selling series of books began with “Little House in the Big Woods,” which chronicled her pioneering childhood in the late 1800s. The books were so well loved that NBC adapted one into a pilot and then a TV series (“Little House on the Prairie”) that aired from 1974 to 1982. “Little House” still airs in syndication in the U.S. and abroad today, and Wilder’s popular books are still in print. Wilder didn’t publish her first book until she was 64. She started out as a teacher at the age of 15, and married Almanzo Wilder (a farmer) at 18. She wrote several articles on farming and rural life in the early 1900s, eventually becoming poultry editor for the St. Louis Star. Later in life, she started documenting her own story, at her daughter’s encouragement. She finally published “Little House in the Big Woods” in 1932 and continued the series about herself and her family, ending with “These Happy Golden Years” in 1943, at age 76.

Nelson Mandela was part of the African National Congress, a group that campaigned against apartheid. After 69 black people were shot dead by police during the Sharpeville massacre in 1960, Mandela and like-minded members of the ANC turned from nonviolence and began a campaign of economic sabotage instead. He was arrested and convicted of sabotage in 1962 and sentenced to life in prison in 1964. In 1980, his friend and fellow lawyer Oliver Tambo launched a campaign to free Nelson Mandela, and 10 years later South African president F.W. de Klerk did just that. In 1994, when he was almost 76, Mandela was elected president of South Africa in the first election that was open to all races in that country’s history. On his 80th birthday he married his third wife, Graca Machel.

British-American stage and film actress Jessica Tandy’s career spanned nearly six and a half decades. In that course of time, she enjoyed an amazing film renaissance at age 80, something unheard of in a town that worships youth and nubile beauty. Jessica enjoyed a 67-year career before her death in 1994. She appeared in more than 100 stage productions and had more than 60 roles in film and TV. She won an Oscar for 1989’s Driving Miss Daisy for which she also received a coveted BAFTA and a Golden Globe.