There is a story that an old woman always feels unhappy, because when the sun comes out, she worries about her daughter's business, because the girl sells umbrella.
But when it rains, she stills feels unhappy for she worries about her another daugther's business. People tell her to change his point of view, when the it is fine, she can feel happy about her second daughter's business and when it rains, she can be happy about her first daughter's business.
In that way, she will be a positive woman every day. We can't change the fact, but we can treat things in another way, so that we can be positive all the time.