In order to more clearly distinguish the various aspects, functions, and levels of the phenomenon of anxiety, a conceptual differentiation is first introduced and explained between affective fear, felt anxieties, and mental anxiety. Affective fear refers to the bodily reaction when directly confronted with danger. Anxieties are feelings of uncertainty and threat that arise when imagining possible dangers. Mental anxiety is characterized by a general awareness of the inherent riskiness of human existence. It can be understood as a deep concern for oneself or others, for one’s own possibilities in life, and for the future of humanity. The central thesis of the book explores how through our thinking, the attitudes we adopt, and the thoughts we continually generate ourselves, we not only shape the mental dimension of anxiety, but can also influence the felt anxieties.