i strongly agree, we are not prisoners of our set points, we can change them

Could it not be thought that the mean behavior toward which we regress is learned as a coping strategy we use to deal with some outside influence and that unless we remove ourselves from situations that provoke us to resort to the habitual behaviors, we are going to continue relying on the course of action because we deem it/them effective enough that they are worth pursuing? If, for example, someone who is under constant fire from their boss likes to chew a spicy flavor of Doritos because the crunching sound and spice make them feel like they are expressing their anger (and ironically, making themselves all the more frustrated, if we are to believe rage expression research findings), then how is this person to be convinced that drinking water somehow is "just as good." It would seem logical that when someone resorts to comfort foods or another emotionally-soothing expression of desire to be comforted that this person is at that very moment considered solely with comfort rather than the most-healthy alternative to their usual behavior set.

I do agree with the suggestion that persons who wish to get and stay happy should essentially withdraw themselves from situations where they may encounter tension by involving themselves in a hobby or other interest in which it is possible to invest a great deal of mental and/or physical energy that would have otherwise been committed to stresses of everyday life. A person's full dedication to a personal interest or any goal bringing about a pleased state is a core idea of Dr. Csíkszentmihályi's research.

I am the happiest person I know! I find one of the best tools in my Happy Backpack is gratitude.
I've had clients turn their lives around, simply by finding their gratitude and focussing on it daily.