Envisioning the future and how you may feel (affective episodic future thinking [EFT]) helps adults to act in favor for their future self, according to manifold experiments. The current study tested whether and how affective EFT also helps children to behave more proactively, that is, to self-initially prepare for an upcoming event. Five-year-old (N = 90) children (data collected from 2021 to 2022) were instructed to mentally imagine how they would feel after successfully managing an upcoming test (positive affective EFT), how they would feel after failing to do so (negative affective EFT), or they were reminded of an upcoming test without a prompt to imagine (control condition, random assignment). Proactive behavior was indicated by children's choice to play one of three games before the actual test (one of the games was announced to be the test game). Mechanisms (e.g., motivation to win, psychological distance, current affect) and moderators (ability of episodically thinking about the future in everyday life, behavioral inhibition, and behavioral approach) for the possible effects of affective EFT were explored. Children in the negative affective EFT condition chose the target game significantly above chance level and more often than children in the control group, whereas children in the positive affective EFT condition did not. This effect was independent of the assumed mediators and moderators. Findings are discussed in the context of the theoretical and empirical literature on affective EFT in adults and suggestions for future studies are given. (PsycInfo Database Record (c) 2024 APA, all rights reserved).