Liz DiMarco Weinmann was sitting in her New York office on the morning of 11 September 2001 when two planes flew into the Twin Towers.
As with many Americans that day, the experience changed her life.
"I looked out the window and saw the buildings fall, and decided I had sold enough soap and cereal," she recalls.
Ms DiMarco Weinmann left her corporate job as a marketing consultant earning a high six-figure salary and spent the next few years trying to find something more meaningful.
She tried non-profit organisations and lobbying in Washington, but nothing seemed to work.
In 2007, at the age of 55, she realised she would have to go back to school and learn how to start her own business. And so she enrolled at New York University's Stern School of Business to study for a Master of Business Administration (MBA).
"It's certainly not the age when most people decide to do it. But interestingly I wasn't the only person in [the class] who was over 40," she says.
According to a study by the Kauffman Foundation, a US start-up support organisation, there are a growing number of people like Ms DiMarco Weinmann in the US - so-called "encore entrepreneurs", individuals who have set up their own businesses in later life.
It found that people aged 55-64 started 23.4% of all new businesses in the US in 2012, up from 14.3% in 1996.
Meanwhile, separate data suggests that among US encore entrepreneurs, women are actually more prevalent than men.
According to a 2010 report by Babson College, a business school near Boston, 10% of US women aged between 55 and 64 had taken steps to start their own business, compared with 7.5% of men.
An ageing US population is one reason for the growing trend in encore entrepreneurs of both sexes - by 2030, at least 18% of the population of the US will be 65 or over.
But the financial crash five years ago also had an impact, as people have simply lost their jobs.
"I know so many people in their early 50s who are being let go, and it is quite a shock," says Ms DiMarco Weinmann, who has written a book about her own experience called Get Dare From Here.
She also runs her own consultancy, the Dare Force Corporation, which helps women over 40 develop new careers.
Ms DiMarco Weinmann says that in this day and age there is no such thing as a job for life.
"You should be making plan B from the time you're 30," she says. "Know what you want to do when the gig is up, know what you want to do in your old age."
Carol Doyel is 54 and had been a successful estate agent for several years before the US housing bubble burst in 2008. She suddenly needed to become a female encore entrepreneur.
"I'm an entrepreneur at heart and it seemed like a good time to start my own business," she says.
Perhaps surprisingly, she decided to launch an online magazine at a time when many publications were going out of print, or struggling to make money on a digital platform.
But Ms Doyel aimed her magazine at an audience she knows well, and one that is much sought after by advertisers - women over the age of 50.
"It's a very desirable demographic," she says. "Women aged 50-plus in the US control about three-quarters of the wealth - they may not own it, but they make the decisions and manage that wealth.
"And as consumers they represent major buying decisions in almost every category from toilet paper to Cadillacs."
The website, called LivingBetter50, caters for a broad audience with articles offering advice from cutting a pomegranate to strategies for a successful media interview.
It gets its revenues from targeted national advertising campaigns.
Ms Doyel says many readers are women who are starting their "second act" because they want to do something different or because of a weak economy.
"Their husbands have seen a reduction in income, or for business owners, a reduction in their revenue, and often that's required women to step up," she says.
"Some of them become the breadwinners. And there are many women who lose their spouses [through death or divorce] and are facing that challenge."
'Make a comeback'
Older people often face a rude awakening when they apply for a new job, says Anne Bahr Thompson, chief executive of Onesixtyfourth, a boutique brand consultancy she started in her mid-40s.
"Every day we see somebody in this age bracket who goes out and thinks they're going to get a job because of their rank or experience," she says.
"But employers are only hiring people in their 30s [or younger] because they're cheaper. No-one is really talking about this."
Instead she says that for many older people, starting up their own business may be a more attractive option than applying for new jobs.
"See this as an opportunity to step into your own power and become all you can be," she says.
"It's easy to feel vulnerable. Remember, however, all the ways and times you've been successful. Write a list of your accomplishments, and focus on what it felt like at the moments you knew you were at the top of your game."
Liz DiMarco Weinmann puts it more bluntly: "Get over the fact you've been dumped by corporate America - it happens to a lot of people.
"But look at all the famous people who went before you and made a comeback!"