As the extent of health disparities in the USA has been revealed, particularly during the COVID-19 pandemic, physicians have increasingly attended to their roles as advocates for their patients and communities. This article presents "spheres of influence" as a concept that can help physicians think strategically about how to build upon their clinical work and expertise to promote equity in medicine. The physician’s primary sphere of influence is in direct patient care. However, physicians today often have many other roles, especially within larger health care institutions in which physicians often occupy positions of authority. Physicians are therefore well-positioned to act within these spheres in ways that draw upon the ethical principles that guide patient care and contribute materially to the cause of equity for colleagues and patients alike. By making changes to the ways they already work within their clinical spaces, institutional leadership roles, and wider communities, physicians can counteract the structural problems that undermine the health of the patients they serve.