Here it is:
There once was a farmer. One day the farmer's only horse broke out of the corral and ran away. The farmer's neighbors, all hearing of the horse running away, came to the farmer's house to view the corral. As they stood there, the neighbors all said, "Oh what bad luck!" The farmer replied, "Perhaps."
About a week later, the horse returned, bringing with it a whole herd of wild horses, which the farmer and his son quickly corralled. The neighbors, hearing of the corralling of the horses, came to see for themselves. As they stood there looking at the corral filled with horses, the neighbors said, "Oh what good luck!" The farmer replied, "Perhaps."
A couple of weeks later, the farmer's son's leg was badly broken when he was thrown from a horse he was trying to break. A few days later the broken leg became infected and the son became delirious with fever. The neighbors, all hearing of the incident, came to see the son. As they stood there, the neighbors said, "Oh what bad luck!" The farmer replied, "Perhaps."
At that same time in China, a war broke out between two rival warlords. In need of more soldiers, a captain came to the village to conscript young men to fight in the war. When the captain came to take the farmer's son, he found the young man with a broken leg--delirious with fever. Knowing there was no way the son could fight, the captain left him there. A few days later, the son's fever broke. The neighbors, hearing of the son's not being taken to fight in the war and of his return to good health, all came to see him. As they stood there, each one said, "Oh what good luck!" The farmer replied, "Perhaps."
(I don't know who wrote this, otherwise I would attribute it.)
One way to look at this is: you have no way of knowing which way fate will go. But you do have control over how you react to it.
Another way to look at it is: being open to all possibilities gives you the most chance to ultimately get what you want.