Sustaining collaboration over time is vital for its effectiveness and long-term success but presents challenges, especially for actors with capacity constraints. This study introduces “capacity tensions” as a central challenge in collaborative efforts, referring to the strain that arises when the capacity needed for effective engagement exceeds the capacity actors have available. This gap creates competing demands, as actors must balance what they can realistically contribute with what the collaboration needs to remain viable and successful. Focusing on a nonprofit collaboration that, despite ongoing capacity constraints, persisted with notable achievements, this study investigates how actors navigate and manage these tensions to sustain their efforts. By analyzing 165 interviews conducted over 11 rounds, participant observations, and archival documents from 2016 to 2020, this study identifies strategies of internal accommodation and external orientation. These strategies enabled actors to “hang in there” by assembling different contributions; tailoring work process; searching for relevant opportunities; and creating spin-off projects. Examining these strategies across three phases of collaboration over five years, this study proposes a process model that offers insights into sustaining effective collaboration despite capacity tensions. These findings provide valuable guidance for practitioners and scholars striving to build sustainable and resilient collaborations.