Lecturing your friend about his negative patterns can make him feel even worse, and he may turn on you. Criticism is difficult for everyone, but it’s especially difficult for someone with negative thoughts and emotions circulating in his head. Trying to vent to him about his own behavior may just escalate the situation and make him feel attacked. Provide a supportive environment to the best of your abilities. If you let your happiness depend on a negative person, it will end in disaster. Keep your emotional distance from a negative friend. Avoid getting sucked into his world and then needing to solve his problems in order to be happy yourself. One of the most effective methods for helping a negative friend, and helping yourself too, is to remain positive in the face of his negativity. This will keep you happy and show your friend an alternative to the way he sees things and acts in the world.  Take a break. Humans can "catch" emotions; in other words, the emotions of people around you are likely to rub off on you. Even if you are a very positive person, if you are around negativity too much, it may make it harder to maintain your positive outlook. Take a break from your friend's negativity sometimes. Another way to maintain your positivity is to stay in tune with your own emotional experience. If you're starting to feel negativity rubbing off on you, check in with yourself and remind yourself that that isn't something you want. For example, "I'm starting to feel angry at restaurant servers because my friend has been complaining for five minutes about ours. I don't have a problem with our server. This anger isn't mine." You'll be more able to sustain your own positivity if you focus on it.  Use humor. Redefining a negative experience in humorous terms can help counteract the brain's natural impulse to focus on the negativity of a situation. The next time your friend starts in on a rant, flip the situation humorously: "I'm sorry your car didn't start and you had to run for the bus. But hey, you did say you've...

===
Write a summary of the previous text in Chinese:
不要对你的朋友挑刺。 为你自己的幸福负责。 展现你的积极。 不要附和朋友的消极。 要有同情心。 保护好自己。 考虑看医生。