In one sentence, describe what the following article is about:

Everybody feels sad or disappointed at some point in his or her life. If you never knew what it felt like to be down, you would have no reference point to understand what it means to be happy. The important thing is to keep a balance in your life between the ups and downs, and not letting the downs spiral out of control. A major reason why people feel inadequate or dissatisfied with their own lives is because they constantly compare their own circumstances with those of people who seem to be better off. What's more, people tend to compare the low points of their own lives with the high points of other peoples' lives, without taking into account that even the most "fortunate" people deal with their own struggles behind closed doors. Rather than comparing your life to people who seem to be better off then you, take a moment to compare your life to people who are suffering from poverty and disease. This will help you notice how fortunate you are, and realize that perhaps a lot of your so-called "woes" are actually quite trivial in the grand scheme of things.

Summary:
Remember that feeling down is a natural part of life. Stop comparing your life to other peoples' lives.