Empathy is a critical aspect of human emotion that influences the behavior of individuals as well as the functioning of society. Although empathy is fundamentally a subjective experience, no studies have yet examined the neural correlates of the self-reported experience of empathy. Furthermore, although behavioral research has linked empathy to prosocial behavior, no work has yet connected empathy-related neural activity to everyday, real-world helping behavior. Lastly, the widespread assumption that empathy is an automatic experience remains largely untested. It is also unknown whether differences in trait empathy reflect either variability in the automaticity of empathic responses or the capacity to feel empathy. In this study, 32 participants completed a diary study of helping behavior followed by an fMRI session, assessing empathic responses to sad images under three conditions: watching naturally, under cognitive load, and while empathizing. Across conditions, higher levels of self-reported experienced empathy were associated with greater activity in medial PFC (MPFC). Activity in MPFC was also correlated with daily helping behavior. Self-report of empathic experience and activity in empathy-related areas, notably MPFC, were higher in the empathize condition than in the load condition, suggesting that empathy is not a fully automatic experience. Additionally, high trait empathy participants displayed greater experienced empathy and stronger MPFC responses than low trait empathy individuals under cognitive load, suggesting that empathy is more automatic for individuals high in trait empathy. These results underline the critical role that MPFC plays in the instantiation of empathic experience and consequent behavior.