My primary research areas are in the fields of Human-Computer Interaction, Ubiquitous Computing, and Health Informatics. The overarching goal of my research is to empower individuals and help them make positive behavior changes through fully leveraging their personal data. Putting people at the center of the data flow, I examine three specific interactions between individuals and their personal data: (1) data collection, (2) data exploration, and (3) data sharing. Using human-centered design methods and mixed-methods approaches, I aim to understand people’s challenges and needs regarding how people interact with data. Based on the understanding, I design, develop, and evaluate web and mobile applications, visualizations, and multi-modal interactions. I apply these approaches to various health contexts, such as improving patient-clinician communication and patient care; leveraging patient-generated data; helping individuals form healthy habits; designing low-burden self-monitoring tools; and providing feedback and visualizations for personal data insights.