Kathryn Schulz considers the "beautiful fact that the underlying theory of the self-help industry is contradicted by the self-help industry’s existence" – that is, we don't really know what a "self" is:
The self-help movement seeks to account for and overcome the difficulties we experience when we are trying to make a desired change—but doing so by invoking an immortal soul and a mortal sinner (or an ego and an id, a homunculus and its minion) is not much different from saying that we "are of two minds," or "feel torn," or for that matter that we have a devil on one shoulder and an angel on the other. These are not explanations for the self. They are metaphors for the self. And metaphors, while evocative and illuminating, do not provide concrete causal explanations. Accordingly, they are not terribly likely to generate concrete solutions.
True, self-help literature is full of good advice, but good advice is not the issue; most of it has been around for centuries. The issue is how to implement it. In the words of the emphasis-happy Robbins, "Lots of people know what to do, but few people actually do what they know."
Previous Dish on the subject here.