Downvoted as a matter of course for the disrespectful lack of a summary. This would have been enough:
only a human being can feel bad about feeling bad
results in a positive feedback loop pushing people into depression.
There is another important information towards the end of the article: different cultures have different connotations of "happiness" -- high arousal positive state (enthusiasm or excitement) vs. low arousal positive state (calm and serenity). The latter can be held for a long time, the former can not.
Thus by defining hapiness as a state of perpetual excitement, you are already sowing seeds of your future disappointment with your life.
(By the way: depression can also have biological reasons, indepenent on the topic of the article.)
http://www.alternet.org/print/books/youre-making-your-depression-worse-self-help-bringing-us-down
TL;DR:
results in a positive feedback loop pushing people into depression.