"I tell them 'well, if you keep practising, eventually you'll get the hang of it," she told a laughing crowd that had gathered for a graduation ceremony at the University of British Columbia on Wednesday.
Isherwood, the most senior female lawyer still practising with the B.C. bar, received an honorary doctorate of laws degree at the ceremony, recognizing her decades of legal work and service to her community.
The Victoria lawyer still runs Holmes and Isherwood, the firm she and her husband opened in 1964.
Her honorary degree comes 64 years after Isherwood walked across the stage at the very same university to receive her law degree.
There were eight women and 200 men in her 1951 graduation class, and she was the first woman to receive the B.C. Law Society's gold medal for top marks.
The senior lawyer was happy to see a more gender-balanced class walk the stage Wednesday.
"Though I must admit, some of them really did look like teenagers," she said in an interview.
Isherwood practises general law, including everything from arranging mortgages and wills to adoptions and separations. But she has always stayed away from criminal cases.
"I left all the criminal stuff to the boys," she said with a laugh.
Some of her most memorable work has been as a legal adviser with the Anglican Diocese of B.C., helping to determine a way forward on issues such as residential schools, female priests and gay marriage.
Law wasn't always Isherwood's chosen path. As a young woman, she was the drummer in an all-girl orchestra, and travelled playing big band music.
Reminiscing about her dreams of being in show business, the nonagenarian shook her perfectly coifed strawberry blonde hair and smiled.
"We thought we were quite good," she said.
Today, Isherwood has a deep passion for the law, and loves the variety it brings.
"No two clients are alike, no two cases are alike," she said. "And the clients themselves are the greatest variety of them all."
Many things have changed over Isherwood's decades in law, but there's one thing she has not fully embraced: she still uses a typewriter instead of a computer.
"Clients are a bit confused when they first come in and see it," she said. "But then they say 'I really missed that clickety-clack sound.'"
Isherwood has also been a role model to budding lawyers. Her nephew, Robert Holmes, remembers wanting to follow his aunt when he was a boy.
Holmes is now a partner at the Vancouver law firm Holmes and King, and still holds his aunt in the highest regard, particularly for her ability to connect with others.
"It's really quite a remarkable feat, to be able to relate and empathize with other people, and to relate and listen, and to build them up," he said.
Standing before the crowd Wednesday in a bright red and blue gown, Isherwood offered similar advice to the graduates, encouraging them to be approachable with their clients.
She also offered the crowd some words of wisdom on aging.
"There's really nothing wrong with getting old," she said. "You just have to keep going and keep breathing."