Before her 50th birthday, Audre Lorde faced cancer for the second time. The black feminist poet had already lost a breast to the disease, and six years later it doubled back for her liver. Though stunned by pain and fear, she declined medical intervention, and instead embraced her own form of self-care: keeping an appointment to teach in Germany, taking in the first Feminist Book Fair in London, and having fun. “I may be too thin,” she noted in her journal, “but I can still dance.”

Lorde died in 1992, but not before putting self-care on the map with her book of essays, A Burst of Light. In it she wrote: “Caring for myself is not self-indulgence, it is self-preservation, and that is an act of political warfare.” In one of her journals, she took the idea further: “I wasn’...