Existential Analysis, as a personal-phenomenological approach, supports the search for personal meanings and answers to questions about human existence. Recognizing the uniqueness of an individual's life, it leads to finding one's own answers to four fundamental questions: 1) "can I be here?", 2) "do I like to live?", 3) "do I have the right to be the way I am?" and 4) “what do I live for?” The Four Fundamental Motivations constitute the theoretical basis of the original 4FM Acceptance Training as a method of group work with psychiatrically hospitalized people with experience of relational trauma who meet the criteria for the diagnosis of cPTSD according to ICD-11. Relational trauma limits or causes the loss of an individual's natural dispositions to be and act, feel and enter into relationships, remain in harmony with oneself and the outside world, and give purpose and meaning to life. It disrupts processes within all Fundamental Motivations (4FM). Hence, the therapeutic relation teaches one to experience one’s own existence, understand oneself, the world and others in relation to the individual context. With deep concern for people experiencing various psychological difficulties, it enables the exploration of complex reality and the search for consent to life. The aim of the article is to review the assumptions of Existential Analysis and the four Fundamental Motivations of Alfried Längle, Frankl's student, which constitute the theoretical basis of the 4FM Acceptance Training.