More than a half of the text are references to another "studies" to convey the fundamental idea, which every biology student should know after the first semester - emotions has been evolved for a purpose - they are signals between sub-systems, so, they are here "by-design", and should not be ignored or suppressed. An emotion is a signal that an action is needed. Actions, however, could (and should) be suppressed, not emotions.
Another fundamental idea is that any self-delusion, including so-called "positive attitude" would sooner or later (but inevitable) lead to a dissonance due to increasing of the distance from reality (an error). This idea has been popularized by the Buddha ("to see things as they are") and formalized by AI theorists - the method of minimizing a squared error (a distance between an expectation and an actual fact) is exactly this.
How much they earn, these "scientists" (a professor of marketing!) who are unaware of the fundamental principles of biological system organization?