These famous people made a radical career change after turning 30

Questions about whether you're on the "right" career path can strike fear into even the most confident person's heart.

But as some of the most successful people prove, you don't have to have it all figured out from the start.

Plenty of highly successful people chose to make major career changes, some even many years into their adult lives.

Here are 19 highly successful people who prove it's never too late to change paths:

Jeff Bezos had a lucrative career in computer science on Wall Street and took on top roles at various financial firms before transitioning to the world of e-commerce and launching Amazon at 31.

Julia Child worked in advertising, media, and secret intelligence before writing her first cookbook when she was 50, launching her career as a celebrity chef in 1961.

John Glenn is best known for becoming the first American astronaut to orbit Earth in 1962. But 12 years later, at 53 years old, he became a US senator in Ohio, a role he held for 24 years. He did return to space in 1998, however, on a nine-day mission aboard the space shuttle Discovery.

Terry Crews has received numerous accolades for his comedy work on award-winning shows "Everybody Hates Chris" and "Brooklyn Nine-Nine." But no one was laughing when they got tackled by Crews during his four-season stint as a defensive player for various NFL teams in the mid-90s.

Martha Stewart was a full-time model until, as a 25-year-old mother, she found few modeling jobs coming her way. After a five-year stint as a Wall Street stockbroker, Stewart turned her love of gourmet cooking and creative presentation into what is now Martha Stewart Living Omnimedia.

Michael Bloomberg left his job as CEO of financial software, data, and media company Bloomberg L.P. at 59 in 2002 to assume the role of mayor of New York City, which he held for 12 years. He has since re-assumed his role at Bloomberg as CEO.

Vera Wang was a figure skater and journalist before entering the fashion industry at age 40. Today she's one of the world's premier women's designers.

Dwayne "The Rock" Johnson transitioned careers not once, but twice. Before he was "the most electrifying man in sports entertainment," Johnson was briefly a backup linebacker for the Canadian Football League's Calgary Stampeders. He ditched the football career and joined the World Wrestling Federation (WWF) in 1996 at 24, which catapulted him to stardom and allowed him to cross over to TV and movies in the early 2000s.

Long before Ronald Reagan became the 40th president of the United States at 69, he was a young, up-and-coming Hollywood actor in film and TV.

Billionaire Spanx founder Sara Blakely sold office supplies door-to-door for seven years in her 20s before her line of slimming footless pantyhose launched to success in 2000. She quit her sales job at 30 to run her company full-time.

Arnold Schwarzenegger has made two major career changes, first when he transitioned from world champion bodybuilder in his 20s to award-winning actor in his 30s, then when he became the Governor of California in 2003 at 56.

Harland Sanders, better known as Colonel Sanders, was 62 when he franchised Kentucky Fried Chicken in 1952, which he sold for $2 million 12 years later. Before serving up his renowned original recipe, Sanders held several odd jobs including country lawyer, gas station operator, and railroad worker.

Before launching viral new media sites Buzzfeed and The Huffington Post in his 30s, Jonah Peretti was teaching middle-schoolers how to use Microsoft Office as a computer science teacher.

Comedian and former 'The View' talk show host Joy Behar has always had the gift of gab, but she didn't get her start in comedy until nearly dying from an ectopic pregnancy in her late 30s persuaded her to quit her teaching job and pursue her dream.

Ray Kroc spent his career as a milkshake-device salesman before buying McDonald's at age 52 in 1954. He grew it into the world's biggest fast-food franchise.

Anna Mary Robertson Moses, better known as Grandma Moses, began her prolific painting career at 78. In 2006, one of her paintings sold for $1.2 million. Previously, she was a housekeeper and farm laborer.

Taikichiro Mori was an academic who became a real-estate investor at age 51, when he founded Mori Building Company. His brilliant investments made him the richest man in the world in 1992, when he had a net worth of $13 billion.

Donald Fisher was 40 and had no experience in retail when he and his wife, Doris, opened the first Gap store in San Francisco in 1969. The Gap's clothes quickly became fashionable, and today the company is one of the world's largest clothing chains.

Tim and Nina Zagat were both lawyers in their late 30s when they published their first collection of restaurant reviews under the Zagat name in 1979. The brand eventually became a mark of culinary authority.