Thanks for the information about how different cultures value happiness, and the implication that the high value Americans place on being enthusiastic all the time might be a bad mistake.
On the other hand, I think the author doesn't get rumination right-- to my mind, the distinctive quality of rumination is focusing on a problem while having lost track of the possibility of a solution.
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.