I'm sure there are many depressed people out there who thought they were happy just prior to the fall as well. Thought does have power, but thinking you are happy, and being happy are not the same entity.
And again we have the matter of happiness being subjective.. what a Tibetan monk considers happiness is not the same as what a wall street exec. considers happiness, which is not the same as what preacher considers happiness, which is not the same as what a jungle dwelling Amazon native considers happiness.
So what is happiness, and why isnt this thread in the religion and philosophy forum