Every January, many of us pony up for memberships to our local gym, where strong, beautiful people lead spin classes and demonstrate how to deadlift. This isn’t a very highly paid job, but, as Jennifer Sappey and Glenda Maconachie found studying fitness workers in Australia, being a fitness instructor provides different rewards.

In 1993, Sappey and Maconachie surveyed fitness workers in Queensland. They were looking at the lack of labor protections in the industry, trying to determine how this affected wages, hours, and working conditions. But they found something unexpected: workers gladly accepting inferior working conditions for the chance to do a job they loved.

In 2008 and 2009, they followed up with some specific question about the appeal of the work. By traditional standards, they found, fitness jobs remained less-than-great. Only 15 percent of industry employees were full-time workers with strong protections under Australian law. And just 5 percent said they were attracted to the industry by financial rewards. In fact, workers were willing to make significant financial sacrifices for their jobs. Fifty-eight percent said they spent more than $1,000 a year on job-related costs like music tapes, footwear, and professional indemnity insurance. For many, fitness work was a second job.

Some respondents clearly indicated the job didn’t pay enough to balance out the expenses. “I love getting paid to stay fit, even though I pay out more for that privilege,” one said. Another acknowledged that “luckily I have a husband to support me otherwise I couldn’t afford to live on the wages.”

So, why did they do the job at all? Many said it was simply fun, or that it made them feel good to help clients improve their bodies. Looking at the explanations fitness workers offered, Sappey and Maconachie found one particularly common narrative: a former fitness client who had worked hard to get a beautiful body gaining the chance to share their success and gain admiration from their former peers.

“I’m motivated to help others feel as great as I do… and make them smile,” one worker told the researchers.

Comparing their findings to Arlie Hochschild’s classic work on emotional labor, Sappey and Maconachie argue that the experience of fitness workers should expand our conception of work. An aerobics instructor isn’t simply trading labor for money—she’s also (perhaps primarily) using her hard-won physical appearance and her enthusiasm for fitness to gain admiration and social status. Similar stories may apply to a variety of other workers, like artists, fashion models, and minor-league sports players.

Sappey and Maconachie write that traditional worker protection laws and labor unions aren’t necessarily equipped to support workers who are more interested in social than monetary rewards. At the same time, they note that this dynamic may mean that psychologically rewarding work is only available to people who have another source of income.

It also means that it’s easy for gym owners to pay low wages, and pocket a relatively large portion of that membership fee you’re paying this January.