There's no rule saying that you have to like everyone you meet. That said, if you have not-so-nice feelings toward someone else, you can still act cordially toward them. Unless you want the label of mean girl -- or mean boy -- pushing your hate aside and putting on a polite face is a must.

Take Notice

The hate that you feel for the catty girl in your chem class, the workplace gossip or the guy who dumped you publicly on Facebook can show on your face. Experts with the TeensHealth website suggest looking inward and noticing the emotions that you are feeling. Taking notice of your emotions can help you to trade in a hate face for a much more cordial expression. For example, saying to yourself -- not out loud -- "I feel angry at Joe because he cheated on me," can help you acknowledge the reason for your negative feelings and then momentarily put them aside so you can take a more polite approach in your interactions with that person.

Proof Positive

Dwelling on negative feelings will keep the hate in your heart and in your attitude. After taking note of your true feelings, switch up your emotions and focus on something more positive. For example, after you've identified the anger and hatred that you feel for your ex-girlfriend, re-focus your attention on positive thoughts such as your new girlfriend, the A that you got on your math test or the raise that you just received at work. The experts with the TeensHealth website point out that the more you think about the happy or joyous parts of your life, the easier it is to have a positive attitude. Use your self-created positive view to keep your negative emotions in check as you work to act cordially in the face of hate.

Perspective Play

If you want, or need, to act cordially to the person who wronged you, try to look at things from his perspective, says communication coach Preston Ni in his article "8 Keys to Dealing with Problem People" on the Psychology Today website. This approach can help you develop some level of empathy for him, making it easier to act in a cordial way. For example, maybe a co-worker lifted your idea and presented it as his own because he was afraid that he'd lose his job, rather than because he was out to get you.

Ignore Rude Behavior

If the person you hate is outright mean, insulting or rude to you, acting in a cordial way may seem like a struggle. When you're left wondering, "Why should I put up with her behavior?" remind yourself that you're mature, classy and won't stoop to an equally insulting level. Instead of letting the other person ignite a negative reaction, don't play into her games, suggests author Donna Flag in her article "Difficult People and How to Handle Them" on the Psychology Today website. Ignore the offense, put on a sweet smile and don't let the person's rude actions get you down.