We investigate work motivation in the unstudied domain of individuals who pursue very long-term goals. We highlight the fact that the preponderance of research findings on the psychology of work motivation is based on short-term studies and discuss the potential relevance to long-term motivation of literatures including long-term thinking and time horizons, long-term goals and goal pursuit, and self-regulation. We adopt the qualitative research strategy of theory elaboration, with a specific intention of elaborating goal-setting theory. Analysis of interview data from a unique sample of scientists and others pursuing goals spanning decades or more yielded a structure of psychological factors that can enhance, support, and sustain motivation for the long term. Reconciling our findings with existing goal theories, we develop an integrative model of motivating factors and self-regulation processes underlying long-term goal pursuit. We discuss the implications, including an expanded focus for our field on motivating people for the long run. Copyright © 2012 John Wiley & Sons, Ltd.