This paper argues that there is an emerging opportunity for artificial
intelligence researchers: the development of technologies that enable
a new type of "proactive health care system" that continuously
monitors "healthy patients" in their homes and motivates lifelong
healthy behavior and health self-awareness. The components of the
system, which would augment but not replace traditional health care, could
be funded entirely by consumers without reliance on the
financially-burdened health care industry. A research prototype of one
component of such a system is described: a preventative monitoring
system for congestive heart failure that uses "just-in-time,"
context-sensitive questioning. The system illustrates how sensors in
the home used for entertainment and communication purposes might also
be employed -- at a negligible additional cost -- for preventative health care
applications.

Preventative medicine, Bayesian networks, context-aware computing, medical expert system.