In this study, we explore the impact of feedback, feedforward, and personality on computer-mediated behavior change. We studied the impacts of the effects using subjects who entered information relevant to their diet and exercise into a database through an online tool. We divided the subjects into four experimental groups: those who received only feedback, those who received only feedforward, those who received both feedback and feedforward, and those who received neither feedback nor feedforward. We found that both feedforward and feedback impacted behavior change but that the effect was much greater for individuals who ranked low in conscientiousness than for individuals who ranked high in conscientiousness. In fact, the magnitude of the effect of feedforward and feedback was nearly the same as the magnitude of the effect of conscientiousness.