I am Distinguished Professor in the Department of Psychological Sciences at University of California, Merced, USA working in the area of health psychology. At UC Merced I am Director of the SHARPP Lab and previously served as Director of the Graduate Program in Psychology. I am Fellow of several scholarly learned societies: the American Psychological Association (APA) Divisions 8 (Social Psychology) and 38 (Health Psychology), the Society of Behavioral Medicine (SBM), the Society for Health Psychology (SfHP) the European Health Psychology Society (EHPS), the Society of Experimental Social Psychology (SESP), and the Society for Personality and Social Psychology (SPSP). I am also a Visiting Professor of Behavior Change in the Faculty of Sport and Health Sciences, University of Jyväskylä, Finland, and Adjunct Professor in the Department of Applied Psychology at Griffith University, Australia. I have previously served as a visiting Professor at the Universities of Rome, Bordeaux, and Grenoble, and Hong Kong Baptist University.

My research applies social psychological theories to predict and change health behaviors. I study relations between theory-based psychological constructs (e.g., attitudes, intentions and motives, self-efficacy, perceived control, self-control, habit, planning, personality traits) and health behavior, and how health professionals can use knowledge of these determinants to promote health behavior change through intervention. I am also interested in developing and advancing psychological theory through theoretical integration, particularly the integration of constructs and processes from social cognition theories, theories of motivation, and dual-process and dual-phase models. In addition, I am interested in research synthesis, particularly testing predictions of psychological theory across multiple populations, contexts, and behaviors using meta-analysis.

I am also an editorial board member of twelve international peer-reviewed journals including Annals of Behavioral Medicine, Atherosclerosis, British Journal of Health Psychology, Health Psychology, International Journal of Behavioral Medicine, Motivation Science, Psychology and Health, Stress and Health, and Psychology, Health, and Medicine. I am former Senior Editor (with Blair T. Johnson) of the Health Psychology section of Social Science and Medicine (2020-2022), Editor-in-Chief of Health Psychology Review (2011-2019), Stress and Health (with Tahira Probst; 2014-2019), and Psychology of Sport and Exercise (with Dorothee Alfermann; 2007-2011). I received a Highly Cited Researcher Awards from Clarivate Analytics six years in a row (2020 to 2025).