Motivating people who are not inclined to engage in health behavior presents a significant challenge to public health practitioners. Although there have been advances in interventions that increase individuals' motivation to engage in health-related behaviors, there is still a relative dearth of evidence as to the processes and mechanisms by which interventions exert effects on behavior. There is also considerable need to identify the moderating factors that enhance or diminish the effects of behavioral interventions. Searching for moderators is important as it will address whether large-scale interventions administered to a population will be effective (a “one size fits all” approach) or whether interventions should be tailored to specific groups with particular demographic, behavioral, and psychological profiles (a “tailored” approach).