Newer approaches in health communication research indicate that understanding the flow of emotional experiences during exposure to fear appeals can clarify their persuasive effects. In a laboratory experiment, the impact of valence shifts during exposure to fear appeals on determinants of health-relevant behaviors were examined. Continuous response measurement allowed gathering real-time data about participants' experiences of valence shifts during exposure. Among the results, a shift from negative to positive valence promoted efficacy perceptions but only for people being personally affected by the health issue. Perceived efficacy, in turn, increased intentions to put recommended behaviors into practice. This suggests that inducing positive valence shifts in health messages improves their effectiveness, especially for relevant target groups.