Satisfying daily life functioning is essential in mental healthcare. Standard assessments focus on symptoms and are designed to detect underlying vulnerabilities. However, they offer insufficient insight into patterns of contextual variability and resilience. Consequently, interventions are planned using incomplete information. The Experience Sampling Method (ESM) is a structured moment-to-moment diary assessing the individual's affect, thoughts, perception, and behavior in the daily life context. ESM helps to understand variation in mental states (e.g., anxiety or sleeping problems) as adaptational processes in relation to contextual challenges (functional analysis). Although ESM has been extensively studied across psychological disorders, the adoption by mental health professionals and their patients remains limited because the 'how to' is unclear. This paper presents a practical guide for ESM application in routine clinical care. It integrates empirical knowledge with expert experiences and provides real-world examples and recommendations for successful implementation. The guide comprises how to engage and motivate patients, and how to customize assessments to the patient's needs. It also includes instructions to interpret results and create an atmosphere of shared decision-making. Experience-sampling technology has merits for patients with various mental health complaints and across healthcare settings, although the exact use and implementation may vary depending on the individual case.