As grassroots user/survivor movements gained traction across the Global North, mental health activists have provided mutual aid for those who consider themselves to be negatively affected by their psychiatrization experiences and for those in search of alternative (non-biopsychiatric) frameworks for understanding mental diversity. In addition to in-person support groups, digital communication has become an integral organizing mechanism for mutual aid actions to support those in mental distress. However, activists have often found both digital and face-to-face communication to be quite taxing to their own well-being-as they negotiate personal capacity to respond to collective needs and practice self-care through limiting their engagements in radical mental health communities. While engaging in an ethnography with a mutual aid community in the United States, I explored the use of "boundary formation" to set parameters for social engagement within digital support and face-to-face encounters. Semi-structured interviews with 14 participants, focus group discussions, participatory observation, and an analysis of digital communication revealed that group members often discussed setting personal boundaries as an act of self-care, a recognition of the pitfalls associated with engaging in group dynamics during times of mental distress, and as a practice to ensure communal longevity. The ways that participants discussed and enacted boundary formation are analyzed in this paper as a way of blocking, redirecting, and restructuring digital and in-person engagements within mutual aid assemblages.