There’s no huge secret about how to be successful in life. Ask just about anyone who has achieved great things what it took to get there, and they’ll tell you the answer is hard work (the internet has rounded up about a million quotes to this effect if you need convincing).

Most often, the trouble isn’t figuring out what you need to do to reach your big goals. It’s actually motivating yourself to keep doing what you know you need to do. You stop going to the gym before you see changes in your body, give up on your startup idea before it gains traction or peter out when you’re only on the first chapter of your book. And just as a million and one famous people have given pep talks on the importance of hard work, a million and one influencers, productivity gurus and super-achievers have offered advice on how to keep going for as long as it takes to actually achieve success.

A lot of this advice is great, but perhaps the tip with the best words-to-insight ratio I’ve ever come across is a quote from a recent episode of Adam Grant’s “ReThinking” podcast. In the episode featuring endurance athlete and Peloton exec Robin Arzn, he offers some of the best advice you’ll ever hear about avoiding burnout while pursuing supersize success. And it only takes him seven words.

In the context of a discussion on how Arzn protects her energy, Grant veers off to talk about the problem with hustle culture as many people practice it today.

“Something that I think so many people get wrong is when they contrast hustle culture with self-care,” Grant says before coming out with this brief but brilliant insight: “There’s a difference between intensity and volume.”

When people hear icons they admire talk about the necessity of “hard work,” they often naturally think “hard work” means many, many hours of effort. There is something to this, of course. Whatever your craft is, it’s going to take a lot of practice and hard graft to get good at it (though maybe not 10,000 hours, as some would have you believe).

But as Grant makes clear, “hard work” doesn’t necessarily have to refer to the duration of the work. It can also refer to the intensity of the work. If you actually dig down into how many super-achievers structure their effort, you’ll see they focus on maximizing the latter.

When Olympic champion speed skater Nils van der Poel wrote up a deep dive into his practice habits, for instance, he stressed the importance of building enough rest and self-care into his routine so he can work at the highest possible intensity when he is on the ice.

Taking two full days a week to just be a normal person and hang out with loved ones, he writes, “made me comfortable with the idea of losing, and so speed skating became much more relaxed and a lot more fun. ... It also made me more determined to work hard because training was not my last resort, it was my voluntary choice endured at my own conditions.”

In “Sweat,” his book chronicling the history of exercise, author Bill Hayes says many top athletes share this understanding that sustainable bursts of intensity beat burnout-inducing volume.

One of the six principles that sustain long-term athletic performance he identifies is “the principle of rest.” Leaving time to recharge in the short term leads to larger gains long term, as you’re able to sustain your practice without burning out.

What’s true for physical work is true of intellectual challenges, too. Research by Harvard’s Rosabeth Moss Kanter and others suggests that the key to professional happiness is working on hard, meaningful problems. Or, in other words, the intensity of your work is key to success. But a host of studies also shows that putting in too many hours actually leads to less overall productivity. The standard 40-hour workweek came about not out of kindness to workers but because data showed that beyond that threshold, working more hours didn’t actually lead to getting more done, thanks to exhaustion and mistakes. In athletics and in business, humans are better able to sustain bursts of effort followed by periods of recuperation than they are endless grinding hours of effort. We produce more in the long run if we leave space for slack and self-care.

Which is why, if you’re chasing success of any kind, you should do yourself a favor and remember Grant’s words. Be careful how you define terms like “hard work” and “hustle.” No one is saying achieving great things is easy or quick. It’s not. But if you think hard work means all-consuming focus and unsustainable hours, then you’re setting yourself up for failure.

As Arzn beautifully puts it in response to Grant’s comment: “Hustle requires the confidence to define what the ladder looks like, what the definition of success looks like. And my definition of success includes my own self-care practices. I’m redefining hustle.”

So should we all.