This study used a self-regulation model of health behavior to explore the impact of risk perceptions and disease-risk symptoms on responses to health messages. Undergraduates with beliefs of high or low vulnerability to heart disease participated in a task that either did or did not induce disease-risk symptoms. Participants were then given a threatening or reassuring message about heart disease prevention, or no message. Participants with high-vulnerability beliefs reported higher exercise intentions only after the reassuring message, and then only in the absence of risk symptoms. However, their exercise rates were increased by both messages and by the symptoms. Participants with preexisting beliefs of low vulnerability reported higher risk perceptions after experiencing the symptoms; only the threat message enhanced their exercise rates.