You perform your job to the best of your abilities, try not to rock the boat and get along well with others. But despite your efforts, you may still come up against a co-worker who stabs you in the back and tries to undermine everything you do. This can negatively affect your job performance and overall well-being. While you can't control or change someone else's behavior, changing the way you interact and react with your undermining co-worker may help improve the situation.

Stay Professional

Although you may occasionally confide personal details to co-workers, it's best to eliminate this behavior with a problem co-worker. Co-workers who undermine are always on the lookout for personal information and juicy details they can potentially use against you. Avoid gossiping with others, especially about the co-worker, no matter how tempting this might be. Even if you think you can trust certain co-workers, you never know what information will circulate around the rumor mill. But it's also important to avoid lecturing co-workers about the evils of gossip – you don't want to come across as a goody two-shoes, says attorney Calvin Sun in an article for Tech Republic.

Understand the Issue

Some backstabbers are just manipulative and undermining by nature. There's not much you can do about these types of co-workers except try to avoid them and manage them as best you can. But sometimes, people have an ulterior motive that may have been triggered by an incident in which you unwittingly played a role, says workplace expert Lynn Taylor in an article for "Psychology Today." Perhaps there's been a misunderstanding, your responsibilities are getting in each other's ways, or you've both become enemies due to mixed-up gossip. Sitting down with your co-worker, identifying the issue, and trying to discuss the problem rationally and calmly may help resolve the situation.

Stay Positive

After you've discussed the issue with your co-worker, it's important to stay positive, despite any reactions. If she decides to respond childishly or spitefully, that's her problem – but you shouldn't sink to her level, no matter how angry or irritated you might feel. In an article for CBS Money Watch, human resources expert Suzanne Lucas advises staying as positive as possible and saying something such as "I'd like to be able to work well together. Let's try and move forward from here." Don't complain, act defensive or display a defeatist attitude.

Document Your Interactions

If your efforts to understand your co-worker and resolve the situation are ineffective, you may need to have a discussion with your supervisor or human resources department. Consult your union representative or employee assistance program if you're unsure of how to proceed. It's important to have specific, detailed documentation to support your complaint and to avoid sounding like a tattletale. According to Lucas, documenting your co-worker's lies and your work is crucial. Showing your boss that you've met certain targets or achieved specific goals, despite your co-worker's behavior, demonstrates your effectiveness and commitment to your work.