The sustainability movement, committed to the health of our natural world, is making a critical contribution to society. While many agree the sustainability movement should focus on the natural world, recent articles call for an additional focus on human welfare. This article proposes that a missing piece of the sustainability movement is a discussion of the role of the human spirit. By focusing narrowly on an examination of the state of the natural world, we are neglecting to incorporate the deep and enduring power of the human spirit to transform our natural and human-made environment and to support change agents in the sustainability movement and other social justice movements. Sustaining the human spirit ensures that we each have the hope, clarity of vision, and courage to do challenging work in complex organizations while bringing diverse stakeholders into the conversation during tumultuous times of change. Sustaining the human spirit will result in sustaining our natural world while also creating communities in which the human dignity of each person is honored.