Some bosses know how to motivate their employees with actionable feedback and advice.

Others take a more passive-aggressive approach, which almost always backfires, says leadership and workplace researcher Zach Mercurio. Bad bosses may frequently use these three common toxic phrases, he says:

1. "Don't forget that you're replaceable."
2. "No one's coming to save you."
3. "You've got to prove yourself."

"There's this old like trope that still goes around in management circles of like, 'Don't think you're irreplaceable. We can get someone else in here.' And I think that's really unhealthy," says Mercurio, author of "The Power of Mattering" and a senior fellow at Colorado State University's Center for Meaning & Purpose.

When bosses use those phrases — or use different words to convey similar messages — they're probably trying to encourage their employees to work harder or go above and beyond to get the job done. In actuality, they come across as threatening and fear-mongering, Mercurio says.

"When people feel replaceable, they tend to act replaceable. They don't show up, they don't come in ... they actually put in less effort," he says. "You actually deplete people's self-esteem and self-worth and sense of capability they need to improve their performance."

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To motivate a workplace, consider setting lofty goals for your employees — goals that may be challenging, but you know they'll be able to meet them. That's a tactic that Lisa Su, CEO of billion-dollar chipmaker Advanced Micro Devices (AMD), uses to get the most out of her teams.

"People are really motivated by ambitious goals," Su told Time in December. "[The] strategy of, 'Hey, let's just do a little bit better here and there' — that's actually less motivational."

And if you see an employee struggling, sit down with them to discuss their productivity before doing or saying anything more drastic, Mercurio recommends. Sometimes, "HR will deploy a performance improvement plan to somebody, and they've never actually had meaningful conversations [with their boss], and they don't have the support to improve their performance," he says.

Those meaningful conversations typically need to include an honest assessment of expectations and performance, rather than attempted motivation that can quickly turn toxic. If you hear that you're replaceable, or that your organization won't support you while you're struggling, you'll probably focus on that takeaway more than anything else, says Mercurio.

If your boss uses these phrases, or phrases with a similar effect, Mercurio recommends documenting the words they've said, the contexts of the statements and how they've impacted you. Then talk to your boss about how they made you feel, saying something like: "When I heard that, I felt really discouraged. I want to do great work here, but it's hard to feel motivated when I feel replaceable," Mercurio says.

If your boss' behavior doesn't change, you may need to consider going to HR, he adds.

"I also think in the midst of this, finding and spending time working with people — colleagues, leaders in other areas — who make you feel that you matter can be helpful," says Mercurio.

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