Generally speaking, the wise regard these sad things as their valuable experiences which are indispensable in their life. What's more, never do they have sadness haunt themselves. Quickly, they get rid of sadness and find new pleasures of life. Thus, their life always seems so fine. On the contrary, some pessimists always have sadness haunt them. Their mind always wanders into past sad events, which results in their moodiness and vexation daylong, and even causes sleepless nights, poor diets, frequent headaches, etc. Obviously, none of these results is what we want.
As a result, there is a great need for us to follow the wise persons' example and learn to rid us of painful memory. As an old saying goes, there are no such setbacks that we could not overcome. Keep in mind that never do you have sadness haunt yourself.