In one sentence, describe what the following article is about:

The last thing you want is to add to your friend’s negativity by being too critical or hostile. If you would like to tell your friend that you think he is seeing a situation more negatively than necessary, think about the best way to say this. Use "I"-statements rather than "you"-statements. For example, “Quit being so negative” is going to have less of a positive effect than “I feel like there’s more to the situation than you’re seeing.” "I"-statements sound less judgmental, which can make the other person more open to hearing what you have to say. What you say isn’t the only important factor. Tone and nonverbal cues are just as important. Yelling or throwing your hands up in defeat are going to increase negativity in the room rather than work to fight the fire effectively.  Gentle eye contact and nodding along to what your friend is saying, if you agree, are great ways to create a positive interaction. Maintain an even tone of voice. Staying calm when your friend blows up may help her realize that there's more than one way to respond to a problem. Research shows that speaking slowly causes people to perceive you as “more caring and sympathetic.” In order to communicate with a negative friend in a way that promotes positivity and keeps you from falling into the same negativity, pay attention to how fast you are speaking. You want to be compassionate and positive in your approach, but that’s not the same thing as allowing yourself to be stepped on. Sometimes a negative friend may try to override your opinions. Maintain a firm stance when it comes to your freedom to express yourself and have a differing point of view. Assertiveness is about meeting the needs of everyone involved, not just one person.  Clearly express your desires, wants, and needs. Use direct language that can’t be contradicted. For example, say “The way that you’re acting right now makes me uncomfortable. I’m going to leave, but we can talk later if you want.” Include empathy. For example, “I understand that you want to keep talking about this, but I’m not comfortable with this conversation, so I’m going to leave.” Set limits. For example, "I am happy to listen to your complaints for five minutes, but then I would like us to change the subject so we don't get too bogged down in negative feelings." If a friend is negatively ruminating on something, change the subject to something you know will cheer him up. Injecting positivity into a situation can be a lot easier and more effective than trying to fight negativity. For example, if your friend is complaining about a bad day at work, ask him if he wants to go bowling or see a movie. Offer to pay for his ticket.

Summary:
Think about your words. Be careful about delivery. Watch your pace. Assert yourself. Change the direction of the conversation.