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By Amy Morin, CNBC Contributor

No matter where you go in life, you're bound to come across toxic people — especially in the workplace.

It might be the teammate who often takes credit for your work or the office neighbor who loves to gossip. These are the people who make it hard for you to give up the bad habits (which I identify in my book, "13 Things Mentally Strong Women Don't Do") that rob you of your mental strength. And if you're not careful, they could ruin your entire outlook on your job.

Here are some powerful tactics mentally strong people use to deal with difficult co-workers:

1. They focus on controlling themselves, not the people around them

It can be tempting to invest a lot of energy into hoping that your team leader would suddenly become more supportive or that your co-worker would stop rambling in meetings, but you can't control what other people do. And wishful thinking will only drain you of time and energy.

So while you can't control other people, you can control how you respond to them. Whether you decide that your best approach is to speak up or that you're better off staying silent, put your energy into taking positive action.

2. They resist the urge to complain

We all have our own ways of releasing frustration, but venting only keeps you focused on the problem and prevents you from creating a solution.

Be especially careful about complaining to your boss. Grumbling not only implies that you have no power over your situation, but it also shows you lack power over your attitude. So rather than complain about your situation being unfair, offer up a solution to the problem.

3. They accept responsibility for how they feel

Saying that your co-worker makes you feel bad about yourself or claiming that your boss makes you mad implies that other people have power over how you feel.

No matter how difficult your co-workers are, don't allow their behavior to dictate your emotions. Accept that it's up to you to manage your emotions, regardless of how other people behave.

4. They don't waste time on unproductive thoughts

Have you ever come home from work and spent the entire evening rehashing a conversation you had with your co-worker? Or spend half of Sunday worrying about having to deal with it again on Monday? If so, you're allowing difficult co-workers to invade your personal time.

If you catch yourself doing this, take action immediately — clean the house, call a friend to talk about something different or take a walk. Do anything else that will change the channel in your brain.

5. They avoid language that implies they're a victim

Saying things like "I have to work 60 hours a week because my co-workers don't know what they're doing" or "I had to say yes because that guy's a jerk" suggests that you're being forced to do things you don't want to do. And that can lead to feelings of helplessness.

Obviously, there are consequences for your actions. But changing your language to recognize that you're in charge can empower you. Acknowledge that you didn't want to work late, but you chose to because you wanted to keep your job or you recognized that you could have said no to someone, but doing so might have been a bad career move.

6. They establish healthy boundaries

It's important to establish healthy boundaries that make your expectations clear. If you get interrupted in a meeting, say, "I was talking and you interrupted. I'm going to finish what I had to say."

Or, if a co-worker constantly comes to you with gossip, say, "This sounds like gossip and I don't want to hear it." People who aren't used to having boundaries set with them are likely to get upset. But setting firm boundaries will save you from stress later on.

7. They practice healthy coping skills

Even when you establish healthy boundaries with difficult co-workers, they can still drain your mental strength. Practice healthy coping skills that will help you stay strong.

Experiment with a variety of coping skills, like gratitude and meditation, to discover what works best for you. Take good care of your health as well. It's impossible to stay mentally strong when you're abusing your body with alcohol, sleep deprivation or junk food.

Don't miss: 13 things mentally strong women don't do, according to a psychotherapist and best-selling author

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