When a paediatrician establishes a trusting relationship with their patient, the chance of a positive outcome multiplies. A calm child, who participates fully in the communicative exchange is more receptive to the clinician's requests and reports weaker sensations of pain. This experience stays with the child, shaping how they approach their healthcare as adults. Our qualitative case study unpacks the linguistic aspects of a 32-minute videoed and transcribed exchange between a paediatrician (co-author) and a five-year-old boy she is preparing for a risky procedure. It asks: what linguistic strategies reduce his anxiety? Non-pharmacological methods are key here, as deep sedation is problematic. Our study explains the communicative techniques that the paediatrician exploits. We identify how they function, and how seemingly disconnected strategies group naturally under a few general principles. This is important for professional development because fewer overarching principles are easier to grasp and subsequently to deploy. Our interdisciplinary approach, which relies on real data, can be replicated and expanded with healthcare professionals to enable them to act concretely on their language productions.