We may be at full employment, but a surprising number of Americans aren’t satisfied with a single source of income as wages remain stagnant.

More than 44 million Americans — or around 13.5% of the country — are picking up side jobs as a way to earn extra money, according to a new Bankrate survey of more than 1,000 adults.

Eighty-six percent of side hustlers do it on a monthly basis, and 36% earn more than $500 each month on the job. A staggering 28% of young adults between 18 and 26 years old are most likely to have a side hustle.

But Sarah Berger, writer at Bankrate, points out that you should use this extra income wisely if you’re really working more to help yourself stay afloat.

“Pay down debt and take care of your monthly expenses first before adding anything to your shopping cart,” she said.

Technology empowers the side hustler

Though the survey did not ask respondents to detail their specific side gigs, Berger pointed out that smartphones have made it easy to sign up for extra work whenever you feel like it.

While traditional gigs like dog walking and lawn mowing are still up for grabs, technology has enabled those with full-time jobs to find other sources of additional income. For example, TaskRabbit lets you sign up to run an errand for someone, be it picking up a bottle of wine or moving a piece of furniture.

Ride-hailing apps have also ushered in a wave of opportunities. Berger noted that if you were to spend 20 hours as a Lyft driver in New York City, you could make up to $700 per week.

Then, of course, there are slightly more passive cash cows, like using Airbnb or VRBO to rent out your room or entire apartment. Many working professionals who end up traveling a lot for their full-time profession can easily rake in a few hundred bucks a week this way. And you have the flexibility of choosing which dates you’d like to list.

The massive benefit of these side gigs is that you have the power to opt in or not (or you can choose to veg out and actually sleep in for once).

The side hustle becomes the full-time job?

Beyond people picking up jobs for the sake of making some extra cash, individuals use side hustles to find their creative outlets in the evenings and weekends. Sometimes these fulfilling side hustles can become full-time jobs.

Berger specifically cited a 24-year-old woman who left her full-time corporate job to make a business out of selling her digital prints on Etsy (ETSY).

“The internet lets you showcase your skills and pick your own hours,” she said. “It’s fascinating how profitable these side hustles have become. I think people are realizing it can be a good way to experiment turning their passions into profit.”