The entrepreneurial urge doesn’t necessarily diminish with age.

As people live and work longer , more are choosing to start a business in their 70s. These emerging septuagenarian entrepreneurs share many motives with younger counterparts. They want to be their own boss, set their own schedules and pursue meaningful projects.

While older entrepreneurs might have lost some stamina, age has benefits. People in their eighth decade can leverage years’ worth of contacts and experience. With their children grown, they may feel free to address what has long bothered them, like clutter and costly in-home care. Or, in the case of the founders of Judson Squared, dull trial lawyers.

“They’re boring as hell,” says Judson Vaughn, 71, an actor and filmmaker. He partnered with attorney Judson Graves, 77, known for his persuasive court performance, to create online courses to teach lawyers how to be entertaining as well as effective.

Self-employment rates rise dramatically as people age. Nearly 30% of employed people in their 70s work for themselves , almost double the share of self-employed people in their 60s, says Cal Halvorsen, an associate professor of social work at the Brown School at Washington University in St. Louis. That translates into about 1.3 million septuagenarian entrepreneurs, he says.

For some, it’s a last hurrah, the culmination of ideas that had been percolating for years. Others are driven by the desire to create a product that will improve the lives of others, which often becomes more important as people age.

Some people feel they have no other choice but to start a business because they need the money and have a hard time finding work elsewhere. Help is more readily available. The AARP Foundation launched a nationwide Work for Yourself@50 program to help older adults with limited income explore self-employment opportunities.

Concierge service

Technology has lowered hurdles for startups, says Donna Kelley , professor of entrepreneurship at Babson College, and lead author of Global Entrepreneurship Monitor United States Report . People can sell products and services from their home and don’t need a lot of startup money.

Charlotte Bishop never aspired to be an entrepreneur. “I didn’t think it would offer a steady income,” she says. Widowed at a young age, with two children, Bishop pursued her master’s, and taught office administration skills at City University of New York. Once retired, friends and neighbors asked for help organizing files and clearing clutter.

Seeing demand for her skills and an opportunity to earn money for her sons when they went to college and then started families, Bishop founded Life Files Professionals to manage documents and organize offices, apartments and computer files.

The business is evolving as she is. Bishop recently began offering concierge services for older adults and family caregivers. She researches long-term care options, organizes health records and arranges grocery orders and deliveries. All of these services can be done remotely, which is more important since she turned 80 this year .

“There is a market and need and I know I can provide it,” she says.

Opportunity beckons

Those with long careers often see the gaps in their field, says Babson’s Kelley. “They see a problem and can leverage their experience and connections to try to solve it,” she says.

George Koenig owned a home-care agency, which charged families for hourly or live-in care, for two decades. The market was strong because of the aging population, but costs were becoming unaffordable .

“I started to see a trend where the cost of care was beyond the average person’s ability to afford it,” says Koenig. “How do you solve that?”

One way: Cut out the middleman.

Koenig, 70, sold his company five years ago and recently launched eCaregivers, financing it on his own, while looking for a like-minded investor. The platform links families directly with care providers to set hours and pay, bypassing agencies like the one he once owned.

Platform tools allow families to monitor shifts, make payments and find backup care. Koenig believes families can save 30% to 50% on care, even after paying wages and all eCaregiver fees.

Mary Rawles wasn’t trying to solve a problem. After retiring at age 65 from her teaching job, she simply wanted to turn her love of fitness into a business. Not knowing how, she joined an online mentoring group and connected with fellow entrepreneurs.

One designed her website and another helped develop a business plan for Fit For The Rest Of Your Life. Rawles began offering strength classes in gyms, offices, online and in her garage. She blogged and posted photos of herself doing push-ups on Instagram.

“It was the funnest time ever,” she says, and rewarding in ways she never expected. She developed new business skills, made friends and helped women get stronger. Rawles, 78, had knee surgery last year but continues to hold workout classes in her garage.

Like Perry Mason

Late-life startups often begin serendipitously, bringing together people who have, through experience, reached similar conclusions.

Judson Vaughn, the actor, met Judson Graves, the attorney, several years ago through a mutual friend. During an initial conversation, the Judsons lamented boring trials.

Vaughn knew acting and filmmaking. Graves, a longtime attorney and interim dean at Emory University School of Law, knew law. He also knew the importance of a good courtroom performance. He would bring medical equipment, videos of surgeries and stage his movements at trial, picking the precise locations for opening and closing arguments.

The two men decided to combine their skills to make an online course for attorneys. “Persuasive Performance Skills for Fearless Trial Lawyers,” which includes clips from Hollywood movies, is accredited for continuing-education credit.

Neither of the men need the money or validation. Graves, who travels with his wife and dotes on his grandchildren, says he had a very successful career and has a very full life.

Vaughn says he could be “sipping mimosas on my porch,” rather than editing film and writing scripts.

So why start a business now?

“The beauty of launching a product or service in your 70s is you have this incredible wealth and knowledge,” says Vaughn. “I very much want to pass on the things we discovered.”

Write to Clare Ansberry at clare.ansberry@wsj.com