Positive thinking is easily tainted by the people with whom you associate. If you are always hanging out with cynical people, don't be surprised if you start feeling the same way they do. That's the way things work.
Misery loves company. People love to moan and groan about things. If you want to maintain a positive attitude, you have to limit your exposure to negativity. If not, negative people will taint you. Their bad attitude and cynicism will influence your thinking even when you try to resist.
The same holds true with stories in the nightly news and on the Internet.
Sensationalized stories get people all fired-up until their emotions get the best of them. Tragic stories like that of a gorilla getting shot and killed while dragging around a kid who fell into its exhibit in the Cincinnati Zoo charge peoples' emotions. People on both sides of the argument go online and take shots at each other. Political debates over presidential candidates like Donald Trump and Bernie Sanders, or Hillary Clinton's e-mail server and Bill's wandering Willy can end what were once cordial online relationships and even real-world friendships.
With news like that, who needs Middle Eastern terrorists and wars?
So much of what we put in our heads is negative. It's no wonder that cynicism is rampant.
If your emotions get the best of you in these incessant political debates and emotional reactions to news and events give you stress, don't engage in the debates and stop watching the news-- it's really all about entertainment.
When a genuine news story that might really be important to hear comes across the airwaves, trust me, you will hear about it. If you want to be aware of what is going on, just do what I do, read the headlines and not much else unless it is something that you need to know. Then, fact check it.
As for friends online and off... surround yourself with positive thinkers. You have hopes and dreams and they will never become realities if you fall into the trap of negative thinking.