No word in the business lexicon suffers from linguistic inflation more than "passion." If you're delivering a pitch to investors or writing a bio for your LinkedIn page, declaring yourself "passionate about" CRM solutions or solid-waste disposal or whatever is practically de rigueur, lest you be seen as someone who's merely in it for the money. Those who bring passion, however obligatory, to their jobs will, it's assumed, work harder and more creatively, sweat the details, and endure any setback.

But maybe they'll burn themselves out working around the clock. Or turn to fraud rather than admit their revolutionary blood-testing machine is a piece of junk. In fact, the relationship between passion and success is a complicated one, and attempts to distill it into self-help slogans or professional advice tend to distort it.

Replacing those distortions with rigorous principles grounded in research is the goal of a new book out this week, The Passion Paradox: A Guide to Going All In, Finding Success, and Discovering the Benefits of an Unbalanced Life. I talked to its co-authors, Brad Stulberg, a former McKinsey consultant turned journalist and executive coach, and Steve Magness, an elite running coach, about what they learned. (This conversation has been lightly edited for length and clarity.)

A lot of this book involves taking conventional ideas about the role passion plays in success and disentangling truth from stuff that just sounds true. Why did you feel like that needed doing?

Brad Stulberg: We really wrote this book for ourselves. We both fall into this category of pushers who struggle to turn it off and struggle to be content. When we started researching it, every single topic we got into, it was like, wow, what science says about passion is the opposite of popular culture and how people think about it. There's so much stuff out there that's wrong and we wanted to try to correct it.

Case in point: "Go big or go home." There's a whole genre of business advice about how to make your side hustle your main hustle. The more you have at stake, the harder you'll work. Your advice is to keep your passion project a side hustle for as long as possible. Why?

Steve Magness: There's something almost mythical about the idea of going all-in, betting on yourself. That mentality sounds really good, but it backfires. When it's do or die, a lot more often, we can't handle the pressure and expectations.

Quite clearly if you look at the research, it shows it's better to not go all-in at first. If you go all-in, yes, you're committed to doing these things, but it almost puts you in this fear mindset where you have to succeed out of fear of failure versus succeeding because that's what you want to do. That shifts the goals and expectations. Again, the research shows it doesn't work as well because you're not playing to win anymore. You're playing not to lose. A far more effective approach is that side hustle where you're cultivating it, but you're not going all-in until you're ready to do it.

Tell me about similarity between choosing a spouse and choosing a career.

Stulberg: We all grow up watching Disney movies under this thinking that there's this perfect person or perfect job out there for you, and if you find that soul mate or that perfect job, your life is going to be great. But what the research shows is most lasting passions or lasting jobs don't feel perfect at first. They're really cultivated over time. You grow it into something perfect.

The problem with having that expectation of finding something perfect is you get stuck in seeking mode, going from one thing to the next, instead of the mode of a practitioner, which is nurturing, nourishing, and developing. The research shows about 70 to 80 percent of people have what's called a "fit mindset," the belief that there's a job out there that represents the perfect fit, or the romantic equivalent, a "destiny belief," but the results are the total inverse. Only like 20 percent of people do find that perfect passion. It's much healthier to have the mindset that it might not be perfect, but if it's good enough at first, it's worth pursuing.

Let's talk about balance--a contentious topic in the startup world. There's the camp that says you can't hope to succeed as a startup unless you're driving yourself to the breaking point, versus the camp that says if you're working 100-hour weeks, it just means you're not working efficiently, probably because you're a zombie from not sleeping. You say the concept of "balance" itself is the problem here.

Stulberg: This is the most important part of the book in my opinion. When people think about balance, they tend to think about it in terms of having some kind of proportionality in their day. I'm going to be great at my job, I'm going to be a great romantic partner, I'm going to have interests outside my career, yadda yadda yadda. The mentality of really caring but also being balanced tends to set people up for frustration because you come home from work and want to be the perfect partner or dad but your mind's on your work, so you beat yourself up. "I can't be balanced, what's wrong with me?" But the other route, just going 100 percent in all the time--that leads to burnout. The science is pretty clear on that.

What you actually want to be cultivating is self-awareness, and by that we mean the power to choose. Do you control your passion or does your passion control you? It might be a family member's wedding or a kid's sporting event, or just the ability to watch a funny movie at night. If you can't make the choice to do that because there's so much inertia pushing you in the other direction, that's when passion can become dangerous and go to burnout.

What often ends up happening in really successful people that also have life satisfaction is if you look at them over the course of any given month or even any given year, they're completely unbalanced. But if you look at them over the course of a lifetime, they're extremely balanced. They're really good at picking the times and spots where they go all-in and then being aware enough to shift.

You cite Elizabeth Holmes, the founder of Theranos, and Jeffrey Skilling, the CEO of Enron, as two examples of passion gone awry. That could be read as making excuses for their actions: "I just cared too much." Why is passion the right framework for understanding them, versus simply as leaders who wanted the same things as everyone else but had fewer scruples about how to get them?

Stulberg: There's some fascinating research in athletes around what's called obsessive passion, which is when your passion shifts from loving the sport to loving the fame and recognition and success. Athletes with obsessive passion are so much more likely to be OK with doping than athletes with harmonious passion. Once you shift from caring about what you do to caring about results, you'll do anything possible to close the gap. Fraud in business is kind of equivalent to doping in sport.

Magness: Elizabeth Holmes is the perfect example. You could see clearly that the perception of the results of what she was doing, the fame and all that stuff, was the driving source. So much so she had things that couldn't work at all and people were telling her it couldn't possibly work, but she wanted the perception that Theranos was changing the world. You get so caught up in that story it blinds you to everything else.

Let's talk about failure. Here in Silicon Valley, there's a good deal of ageism, particularly around who gets money from venture capitalists. You'll hear that experience can be a negative because failure makes entrepreneurs conservative and VCs only want to bet on hyper-ambitious founders who think they can do the impossible. You say the research shows past failure can be a good predictor of future success.

Stulberg: There's a concept coined by a guy named Gary Klein, who's a collaborator of the well-known behavioral economist Daniel Kahneman. It's this notion of what he calls a pre-mortem. A post-mortem is after something goes terribly, the team gets together to discuss what went wrong and how to fix it. A pre-mortem is the opposite. Before the endeavor starts, you say, here are all the ways it can go wrong. Pre-mortems are really effective and they're shown to work, but there's nothing like actually going through a tough failure.

There's a difference between knowledge, which is knowing something intellectually, and wisdom, which is knowing it in your bones. When you fail, you know it in your bones. With almost any company, there are going to be points where you're either close to failure or have failed. Unless you've walked that road, the decisions you make in those instances won't be as wise. Yeah, maybe you won't be as willing to take the biggest risks upfront, but sometimes not taking the biggest risks upfront is the right move.

Magness: It's like anything. Any sort of adversity allows you to grow. There's some awesome research in the sporting world that connects to entrepreneurship. They looked at professional soccer players and found the ones who made it had to deal with more challenges and more adversity growing up than the ones who got really good but didn't quite get to the professional level. As a coach, I see this all the time. The kid who never loses or never fails going through high school or college, they don't end up making it at the highest level because the moment they face that first adversity, it throws them for a loop. Whereas if you've dealt with it a little bit before, you've learned, OK, this kind of sucks, but I know how to figure my way through these things.