In May 1948, while holding church meetings throughout Navajo and Apache communities in Arizona, Kimball suffered severe chest pain from a myocardial infarction ("heart attack") after spending an afternoon struggling to lift an automobile out of deep sand.
In early 1950, Kimball, who had never smoked or used tobacco, began experiencing persistent hoarseness and, after a physical examination, underwent a biopsy of a white spot in his throat.