This paper presents results toward our ongoing research program into hands-off assistive human-robot interaction. Our work has focused on applications of socially assistive robotics in health care and education, where human supervision can be significantly augmented and complemented by intelligent machines. In this paper, we focus on the role of embodiment, empirically addressing the question: ``In what ways can the robot's physical embodiment be used effectively to positively influence human task-related behavior?'' We hypothesized that users' personalities would correlate with their preferences of robot behavior expression. To test this hypothesis, we implemented an autonomous mobile robot aimed at the role of a monitoring and encouragement system for stroke patient rehabilitation. We performed a pilot study that indicates that the presence and behavior of the robot can influence how well people comply with their physical therapy.