INTRODUCTION: Adolescent psychology is embracing intensive longitudinal methods, such as diaries and experience sampling techniques, to investigate real-life experiences. However, participants might perceive the repetitive self-reporting in these data collection techniques as burdensome and demotivating, resulting in decreased compliance rates. In this tutorial paper, we present a user-centered approach aimed at making participation in experience sampling and daily diary studies a meaningful and fun experience for adolescents. METHODS: In three major research projects that took place between 2019 and 2023, more than 4,000 Dutch adolescents participated (12-25 years old). To improve the participants' user journey, adolescents were invited to codesign our studies and share their expertise in interviews (n = 459), focus groups (n = 101), design decisions (i.e., A/B tests, n = 107), pilots (n = 163), exit interviews (n = 167), and by answering user experience questionnaires (n = 2,109). RESULTS: Across projects, we discovered five different main intrinsic and extrinsic motives to participate in intensive longitudinal studies: (1) rewards, (2) fun and interest, (3) helping science or the greater good, (4) helping the scientist or another person, and (5) gaining self-insight. We provide concrete examples of how we tailored our study designs to address these specific motives to optimize youth engagement. CONCLUSIONS: The engagement of adolescents in intensive longitudinal studies can be enhanced by making it a meaningful and enjoyable experience, aligned with their own motives.