  We present Activity River, a personal visualization tool which enables
individuals to plan, log, and reflect on their self-defined activities. We are
interested in supporting this type of reflective practice as prior work has
shown that reflection can help people plan and manage their time effectively.
Hence, we designed Activity River based on five design goals (visualize
historical and contextual data, facilitate comparison of goals and
achievements, engage viewers with delightful visuals, support authorship, and
enable flexible planning and logging) which we distilled from the Information
Visualization and Human-Computer Interaction literature. To explore our
approach's strengths and limitations, we conducted a qualitative study of
Activity River using a role-playing method. Through this qualitative
exploration, we illustrate how our participants envisioned using our
visualization to perform dynamic and continuous reflection on their activities.
We observed that they were able to assess their progress towards their plans
and adapt to unforeseen circumstances using our tool.
