The era of pervasive computing brings with it a grand challenge: Pervasive applications must adapt to the dynamics entailed in human behavior and constantly changing computing environments. In this paper, we propose Adaptable Pervasive Flows as a novel technology that goes far beyond existing approaches for adapting pervasive computing systems. APFs model applications in a fashion similar to classical workflows while being situated in the real world. The notable advantage of this is that applications as well as their environment can be adapted proactively based on knowledge about future tasks. We introduce the visions, concepts, and challenges of this emerging approach.