There are lots of ways to stay positive in a world that inundates you with the negative.
If the world looks bad, think about how far the human race has come in such a short time. The world is 4.5 billion years old, life is 4 billion years old, multi-cellular life is 500 million years old, things resembling humans have been around maybe a million years, and in a mere few thousand years we have built an incredible, awesome civilization. There is cruelty and stupidity still, but we are not long down from the trees.
If the daily news is bad, remember that it's bad news that gets the attention. It's newsworthy
because it's bad. Most things that happen in the world are good or benign, but they get little attention. There are plenty of places on the Internet to find good news or inspiring stories. As an example,
here is a blog run by a friend of mine who is a professor at the University of Richmond (I also write for this blog, which helps me to feel positive-- not only am I bringing something important to peoples' attention, but the research is inspiring).
There are also things you can do personally to feel more positive by contributing to making the world a better place. Get a job that helps people, such as in the health care field (even if it's in a supporting role, like mine). Volunteer for charity work. Or just randomly help complete strangers when they need it. Speak out for kindness and open-mindedness when needed. Being a part of what's positive in the world will make you feel positive.