Why are people optimistic about their futures, continuously assuming that their futures will be full of the positive outcomes they desire and devoid of negative outcomes? This paper concerns the proposal that desire, represented as affective reactions to potential future events, causes optimism for the future. We propose that positive or negative affective reactions to future events innervate motivations to approach or avoid the events. These motivations can be satiated by judging that events that elicit positive affective reactions are likely to occur and events that elicit negative affective reactions are unlikely to occur. The tendency to be optimistic thus results from emotional processes that occur largely outside of conscious awareness. We discuss recent evidence that supports these propositions, the import of understanding optimism as the result of emotional processes for judgment and decision research as well as attempts to improve decision-making, and remaining unresolved issues.