A little over a year ago, a high-performing specialist at one of the largest technologies companies — we’ll call him Santiago — was given an opportunity no high performer could turn down: an opportunity to play a manager role on a project he really cared about. The director told him, “You care about this; you lead it.” So he did, and all seemed to be going well — even though he was planning a significant company-wide event at the same time, a role he had volunteered for.

“We had a really important conference call I had spent a lot of time preparing for. The call went well, but when I finished the call, I realized I was feeling really sick,” Santiago recounts. “It got worse after that. I went to the doctor later that day, and he told me I had pneumonia. I ended up in the ER the next morning and couldn’t work for the full next week. It was a shocking moment for me. I’m young and healthy, but I realized that if I push myself, I will burn out.”

Unfortunately, this isn’t an unusual experience for high performers: A five-year study in the UK found that the mental health of 20% of the top-performing leaders of UK businesses is affected by corporate burnout.

It’s easy to blame burnout on the high performers themselves. After all, the stereotype is that these overachievers say yes to more work even when they’re already at capacity. They routinely put work first, canceling personal engagements to finish the job.

While such habits may be partially to blame, this isn’t the full story. In my experience, many companies and leaders engage in three common practices, often unknowingly, that make top performers even more likely to burn out:

They put high performers on the hardest projects. “The most obvious difference between high performers and their peers is that high performers are put on the hardest projects over and over again. There are no ‘softball’ projects,” says a high-performing manager at a leading strategy and management consulting firm, who we’ll call Lisa. It makes sense: Of course you’d want your best people on the most important projects. But if you keep going back to the same small group of people time and time again, you’ll run the risk of wearing them out.

They use high performers to compensate for weaker team members. Lisa describes another unique characteristic of the experience of high performers: “You’re seen as an exemplary employee, so you’re expected to support lower performers and mentor others.” A senior manager from a leading technology company, who we’ll call Karen, recounts her experience on a project where this was true: “I spent a lot of time trying to coach and mentor them and quite honestly taking on a lot of their work because you feel that is what you’re supposed to do when others are struggling.” While many star performers do enjoy mentoring others, they understandably start to feel resentful if they think the boss is letting poor performers off the hook.

They ask high performers to help on many small efforts unrelated to their work. “As a high performer, you have demands as a culture carrier, a mentor, and a resource for others,” Lisa says. Similarly, Karen describes how this practice affects herself and her high-performing team members: “They are constantly being asked to help in small ways. ‘You’re good at making slides. Can you make this one slide?’ ‘You’re good at WordPress. Can you add this page?’ I’m just realizing how much time I’ve spent on all these one-off requests the last few weeks. And that’s why I don’t feel like I’ve gotten anything done.” While this issue is often framed as a personal problem for people who don’t know how to set boundaries or say no, it’s more fairly seen as an organizational problem where the most hardworking people are “rewarded” with more work.

To fix this, managers can start by becoming more aware of how these practices are affecting their organizations and looking to scale them back when possible. Beyond that, employers and leaders should look to three other strategies to help them support their high performers for the long term: