When Alicia McElhaney first moved to New York last year, she was making $40,000 and felt like she'd made it. But within five months, reality hit her with some pretty major medical expenses -- and she knew she had to find some side hustles to supplement her income.

A recent survey from Bankrate showed that more than 44 million Americans have a side hustle. The majority are Millennials -- adults aged 18 to 34.

And women are side hustling more than men, according to a study from Harvard University.

But women pursue extra gigs for different reasons than men do. The Bankrate survey showed that about 69% of women say they use the extra money from a side hustle to help pay for living expenses, compared to just 42% of men.

In addition to the 40-odd hours McElhaney worked in her full-time job, she took on three additional side hustles: selling clothes on Poshmark and Ebay, writing freelance pieces and walking dogs on the Wag app.

She also signed up to work at her local yoga studio, so she wouldn't have to pay for exercise classes.

"It's embarrassing. You look at yourself like, 'Why can't I make money?' and 'Why can't I have it together enough that I make enough money in my full-time job?'"

Doing it for the money

"For some people, having a side hustle is a good opportunity to turn passion into profit or to make some money on the side," said Sara Berger, author of "The Cashlorette" blog at Bankrate. "But for a lot of people that's not the case."

When Kate Dore first moved to Nashville, she was juggling an unpaid internship and two part-time gigs: waiting tables and selling beer at Nissan Stadium, home to the Tennessee Titans.

Over the next two years, she went on to score two more jobs in the music industry, while constantly working side gigs -- contractor at Eventbrite, personal finance blogger, freelance consultant and more. Soon, she was working every day, averaging more than 70 hours of work per week.

Dore says she did it for the sense of financial security and to protect against layoffs.

"I have this paranoia. I was laid off at a young age and saving is important to me,'" she says. "And it wasn't that I wasn't making enough money, but multiple streams of income made me more comfortable."

Related: How to find (and snag) a hidden job

While there's nothing wrong with making extra money, working too many hours can lead to serious burnout.

Last year, Dore was heading in that direction. In July 2016, after another layoff, she decided to pursue freelance writing full time. Now, she's very wary of ads or promotions that glamorize side hustle life -- she knows the downsides all too well.

"I'm very protective of my time because I've been burned out by side hustles more than once and I've seen the toll it's taken."

After a year and a half juggling her multiple side hustles, McElhaney eventually found a new job that paid her more -- and best of all, gave her back the free time she had lost to her side hustles. She still freelances occasionally and continues to work at the yoga studio.

But her clothes are staying in her closet. And she hasn't walked a dog in months.