This chapter describes the importance of the therapist’s mindful presence and physiological regulation in the therapeutic relationship. The authors emphasise the importance of the therapist’s mindful state of consciousness during the therapy session for effective psychotherapeutic work. They introduce the phrase “The therapist first”, emphasising that the therapist should primarily bring their mindful attention onto themselves, starting with mindful awareness of their own physiological state. By being mindfully aware of their physiological states, therapists regulate themselves and keep themselves within the window of tolerance. From that state of physiology and mind, they are then able to be mindfully aware of the client’s states and lead them to mindful awareness and physiological regulation. The authors provide guidelines for the regulation of hyper and hypoarousal. The main part of the chapter is the vignette of a psychotherapy session, where the methods of mindful awareness and physiological regulation are systematically and practically shown step by step, in seven phases. By being mindfully aware in the session, the therapist regulates herself, stays present and within the window of tolerance. She leads the client to mindful awareness of body and emotions, which results in reaching the memory of a traumatic event, new insight, and corrective relational experience.