One form that mental time travel takes is fantasies about the future. Research to date has not established when people generate fantasies that depict an imagined future as particularly positive. We identify need state as a variable promoting positive fantasies about relevant stimuli (i.e., those that could address the need). In four studies, people with an aroused need (or with a stronger need) generated more positive fantasies depicting idealized future scenarios that were relevant to addressing the need, compared with people without this need (or with a weaker need). These results held for a variety of needs (meaning in life, drinking, relatedness, and power) and whether needs were manipulated (Studies 1–3) or measured (Study 4). The findings shed light on when and why people depict imagined futures as particularly positive. Copyright © 2012 John Wiley & Sons, Ltd.