I think you have it backwards. What you focus on expands. An attitude of gratitude focuses on the good in your life, expands it, and increases happiness.
OK. I am a contrarian. What if there is little good in your life? Should you be grateful for Charlie Parker (mentioned in the article)? Really, what do I care about heroin addict Charlie Parker?
In the same mold, I’m grateful for Mick Jagger, and I have no reason to suspect it wasn’t he hisself, sending me Happy Thanksgiving greeting on Fakebook. But what does such gratefulloness mean?! Nothing as far as I can see.