Dressed in a stained sweatshirt and serious workboots, brown hair swept up in a messy ponytail, Meghan Nemes carefully removes a cafeteria tray covered with vegetable scraps from the cage of an enormous tortoise named Rob. Then she scrubs the concrete floor, hoses it down, sweeps, and puts the food back.

“I already cleaned him once, but he decided to pee,” she says.

Nemes has a degree in zoology and nearly a decade of work experience. She estimates that she spends 90 percent of her day scrubbing, sweeping, mopping, and disposing of the feces of dozens of species of animals. Yet, when she talks about her work, she practically vibrates with excitement.

“I have always wanted to work with animals,” she says. “You have to be able to go with the flow. You have to expect the unexpected.”

In a 2009 paper for Administrative Science Quarterly, J. Stuart Bunderson and Jeffery A. Thompson studied zookeepers and found that the profession was about the closest anyone in the modern, secular world comes to having a calling—the sort of intensely meaningful career that Martin Luther said could turn work into a divine offering. Zookeeping is dirty, repetitive, and poorly paid. And yet people volunteer for years, move across the country, and accept major sacrifices in their personal lives to be able to do it.

These days, the idea of meaningful work is thrown around lightly at industry conferences and in management manuals, mostly as a way to motivate employees. It’s also widely mocked by low-level workers in cubicles whose jobs often feel exactly the opposite of meaningful. And yet, it’s hard to escape the idea that the thing we spend 40, or 50, or more hours at every week really ought to matter.

I wanted to see what really meaningful work looks like. So this March, I went to Meghan Nemes’s workplace, Capron Park Zoo in Attleboro, Massachusetts. It’s a small place, run by the city and tucked behind a playground. When I got there the snow was just beginning to melt and a few hardy families were wandering around the lion habitat and otter pond.

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Nemes tells me she arrived at 7:30 this morning. The first thing she did was to check on all the creatures under her care.”If anything is unusual you’ll notice it right away,” she says. “You have to know the animal, the normal cricks in their walk, if their poop is soft.” Her cleaning affects the animals’ well-being too, she says. She has to choose the right soap and the right time to take care of each cage. If she plays music while she works, she checks to see how the animals react.

In interviews with zookeepers, Bunderson and Thompson found that their feelings about their work ran much deeper than a standard survey metric like job satisfaction could capture. Again and again, they used phrases like “I knew this is what I was meant to do” and described a pull toward work with animals starting in early childhood. The sense of calling also came with a feeling of moral obligation. Zookeepers described an intense dedication to the animals they worked with, and to the zoos’ mission of promoting conservation and breeding endangered species.

Nemes takes pride in the breeding programs that Capron Park, and most US zoos, are part of. She tells me about the black-footed ferret, which was saved from extinction thorough captive breeding and has been reintroduced in the wild. “That’s amazing,” she says. “Extinct is forever.”

Day to day, Nemes’s favorite part of the job is training the animals. The things she teaches them aren’t tricks, she says. They’re behaviors that make their lives in the zoo easier. She works with the zoo’s leopard, Lacy, teaching her to present her hip for injections so the zookeepers don’t have to use the potentially painful, traumatizing tactic of shooting her with a dart gun.

This is the sort of thing Nemes broods over as she mops the floors. “When my animal gets stressed, I get stressed,” she says. “I go back and think ‘how could I have done that differently to allow the animal more choices?'”

An intense sense of duty is something any employer would love to get from employees, particularly if it means they’re so dedicated they don’t worry much about low pay or tough working conditions. Bunderson and Thompson refer to this as the “double-edged sword” of meaningful work. Zookeepers sometimes care so much about their job that they accept being exploited (though they do also tend to hold their employers accountable for treating the animals well).

This is what makes any talk of meaning in the corporate world reek of cynical manipulation to lots of workers and observers. The Wall Street Journal recently reported on companies touting a higher purpose. One travel business casts its mission as contributing to “peace on earth” through cheap plane tickets. An accounting firm asked employees to design posters with slogans like “I support advances in medicine” (by doing the taxes of brain surgeons and scientists). In the New Republic, Joe Keohane described other ways companies try to bring meaning to the job: meditation sessions, poetry, and invitations to employees to convey their feelings about their jobs using Legos. He mentions a statistic that managers like to quote: engaged employees generate 147 percent higher earnings per share. In other words, “meaning” makes workers more productive without the need to give raises or offer better working conditions.

In a 2009 paper for the Journal of Business Ethics, organizational researchers Marjolein Lips-Wiersma and Lani Morris criticize management literature for assuming that leaders can get workers to care deeply about their jobs by instituting a particular sort of culture from the top down. They also investigate why some jobs really are meaningful to employees. Drawing on several different veins of prior research, they suggest a number of interrelated factors. In some formulations, meaning must come from the worker’s own beliefs rather than being imposed from above. In others, it must allow them to act in ways they consider moral, or must serve a cause beyond the individual, “making the world a better place to live in.” Still other research argues that meaningful work requires individual dignity—it must be compensated justly, allow for a balance with outside commitments and involve choice and the development of skills. Clearly, achieving all of this is a tall order.

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After talking with Nemes, I head into the kitchen, where another zookeeper, Siobhan McCann, is cutting vegetables for the animals’ meals. She tells me everyone takes turns spending a day on the task, and she doesn’t mind it. “I like prep,” she says. “I take it as an actual chef’s kitchen.”

McCann started volunteering at a zoo in her native California when she was 14. She’s been doing the work ever since, except for a year and a half when she became the director of an animal shelter. That was work she believed in too. But for McCann dealing with abused and neglected animals day after day was too much. “It really beats you down,” she says.

Being away from the physical work of zookeeping was unpleasant too, she says. She gained weight and felt bad. Now she’s happy to be back at a zoo, where part of the job’s meaning comes from the skills she gains and uses each day. She went to Thailand for a week to work with tropical birds called hornbills, and she goes to conferences and workshops when she can. She says she doesn’t mind working weekends and holidays, and she’s thrilled to get the chance to work with animals she hadn’t known much about before. “It’s enriching for me because then I have to get up on my game about their natural history,” she says.

A little while later I get the chance to see the zoo employees’ intense focus on their animals play out in dramatic fashion. Head keeper Stephanie Mitchell invites me to watch her help the zoo’s part-time veterinarian, Lisa Abbo, conduct an annual exam on a tiny owl monkey named Mango.

The vet checks in with Mitchell as she weighs the monkey. “She does seem thin, doesn’t she? She seem like she’s eating OK?” She asks if Mango was the one who suffered from bouts of diarrhea a while back. No, Mitchell says, that was the male owl monkey.

As she intubates Mango, giving her gas anesthesia, Abbo coos over the little creature’s long fingers. “I love their hands,” she says. “You’ll hear me gush over and over. Every animal is so cool.”

But as the monkey lies on a table to have X-rays taken, Abbo’s voice suddenly turns serious. She calls for Mitchell to bring over a drug to reverse the anesthesia. Then she places an oxygen mask over Mango’s face.

A couple of minutes later, she sighs with relief and tells me I’ve witnessed a “slight anesthesia emergency,” the first of its kind she’s experienced in the six months she’s been working at the zoo. Lying on the table, Mango’s heartbeat had become weak. The most common cause of preventable death from anesthesia is inattention, Abbo says, which is why it’s crucial to be constantly on point even during routine procedures.

“I’m sorry, honey,” she tells Mango, slipping her back into her plastic carrier and letting Mitchell know they should keep an eye on her since the bad reaction to the anesthesia could suggest an underlying condition.

The job of a zookeeper provides a sense of meaning in ways that many careers don’t. It’s a chance to do something that matters on the enormous scale of species preservation and at the tiny level of a little monkey with a fading heartbeat, while learning new skills all the time. And yet, it’s striking how quick most workers are to find meaning in jobs where the appeal is much less obvious. In a 1987 essay for the Journal of Business Ethics, A. R. Gini and T. Sullivan reflect on an apparent contradiction. Workers consistently tell researchers that they find their jobs “physically exhausting, boring, psychologically diminishing or personally humiliating and unimportant.” And yet, most also say that even if they suddenly received enough money to live comfortably without working, they wouldn’t quit. Gini and Sullivan note the powerful theme among Western thinkers, from Karl Marx to Pope John Paul II, that work is how each person creates an identity within the human community.

Writing for the Fernand Braudel Center in 2011, anthropologist Sidney W. Mintz offered a striking example of people finding meaning even in highly exploitative conditions. He described men who dug irrigation ditches in sugarcane fields taking great care in the clothes they wore to and from the fields, and in fashioning and decorating their shovels.

Mintz writes that workers were “undernourished, undereducated, exploited,” and that they were well aware of the oppression and injustice that marked their work. And yet, he writes, that did not prevent them from being proud of what they accomplished.

“People do extract meaning from their acts; they can take pleasure in their work, even if that work is physically demanding and difficult,” he writes. “And they can do so in the modern world, if the work they do is perceived by them as socially valuable.”

If meaning is the thing that makes us work well and with satisfaction, even if it means spending Christmas morning cutting up lettuce for a tortoise, it’s not the sort of thing that can be served up in a corporate mission statement. It’s probably something that’s different for everyone. For some of us, being able to keep our families well fed can mitigate dull routines without much opportunity for self-development. For others, doing work that helps someone else in a concrete way can make long hours and low pay seem worthwhile. And there’s certainly a continuum from a job that’s desperately meaningless to one that’s illuminated with purpose.

In general, though, it seems like a few basic building blocks of meaning are the ability to use skills we can be proud of, pay and working conditions that feel halfway fair, and work that is useful—or at least not actively immoral. If these aren’t part of a job, the employer is likely to be hard-pressed to bring meaning to the workplace.

After Mango’s ordeal, Mitchell and Abbo keep a close eye on her. Before long, she’s fully recovered and eager to gobble up chunks of sweet potato. Then, Nemes helps the vet examine another tiny primate, a pygmy loris who they’ve recently discovered is pregnant. Nemes delights in the way the loris helps herself to crickets from a plastic cereal cup. It’s the last hour of her Sunday-through-Thursday workweek, though she will spend tomorrow working her second job as a bartender. She says that will be relaxing compared with the energy level she keeps up at the zoo, taking care of the animals and sharing her enthusiasm with visitors.

“I’m exhausted,” she says, grinning hugely.