Motivational and cognitive processes of behavior change with respect to the area of exercise adoption were investigated. A total of 778 men and women, recruited from four worksites, answered a 40-item questionnaire consisting of statements based on constructs from the trans-theoretical model of behavior change. Principal-components analysis identified two factors--one a 6-item component representing avoidance of exercise (Cons), the other a 10-item component representing positive perceptions of exercise (Pros). Analysis of variance showed that the Pros, Cons, and a Decisional Balance measure (Pros minus Cons) were significantly associated with stage of exercise adoption. Results are consistent with applications of the model to smoking cessation and other areas of behavior change. Distinctions between exercise adoption and behaviors such as smoking cessation, weight loss, and alcoholism are discussed.