The epidemic of physical inactivity is an important societal and individual problem. Despite the well-documented health effects of physical activity, only 22% of the population exercises regularly enough to get the physiological and psychological benefits (S. N. Blair, 1993, Physical activity, physical fitness, and health. Research Quarterly for Exercise and Sport, Vol. 64, pp. 365–376.) Why does 78% fail to do so? The problem is largely psychological and attributable to the processes of nonconscious and conscious mind. This paper reviews research on how nonconscious and conscious processing affects human behavior in general and exercise behavior in particular. Although there generally is no question about the effect of the nonconscious mind on human behavior, “unconsciously operating motives” in and of themselves are incapable of igniting and sustaining this complex behavior—at least until the behavior has been repeated with regularity and long enough to become consistently prompted by situational cues (as is the case for 22% of the population). There is even some evidence to suggest that the nonconscious mind actually works against exercise by embracing cues and excuses for not exercising. A related problem for both the nonconscious and conscious mind, especially that of the occasional exerciser (54% of the population), is that exercise poses a threat to one's sense of freedom and choice (i.e., “you must do it or else”). The resultant psychological reactance leads to attempts to restore this freedom, but it is often accomplished by giving in to temptations (e.g., TV watching). Although people recognize fitness and health as important human conditions, they often pursue these goals by using exercise as a means toward another end (e.g., to lose weight). In doing so, they struggle cognitively with their need for autonomy while trying to balance it in interpersonal and leisure contexts. Such struggle depletes finite self-control resources and makes people more vulnerable to temptations. The net result is that both the nonconscious mind and the conscious mind fail to turn most people into rational thinkers and “self as doers,” who would do what is best for their health.