Background: Previous research reported the effectiveness of a curriculum-based self-care intervention for students administered in the context of a course on behavior change. Purpose: The study evaluated the effectiveness of the self-care intervention for learners in a publicly available massive open online course (MOOC), who completed the course during the COVID-19 pandemic. Methods: Participants were 216 learners enrolled in Coursera's Health Behavior Change -- From Evidence to Action in March 2020 -- January 2021. The intervention consisted of behavior change assignments designed to increase health-promoting behaviors within three domains (nutrition, physical activity, and mental health). Course assignments were to apply behavioral principles to modify health behaviors. Outcomes included measures of physical wellbeing, depression, anxiety, perceived stress, and self-efficacy. Results: Health promotion behaviors and measures of physical and mental health showed significant improvements over the course of the semester. Discussion: The study provides support for the effectiveness of a brief self-care intervention for learners in a publicly available MOOC. Translation to Health Education Practice: This publicly available intervention can support learner well-being in a variety of academic programs, community, or workplace settings.