1. . The Base-App (BA) condition (i.e., Group D; so named due to the factorial design used in this study) will receive only a base-level smartphone app that contains three components common in computerized behavioral interventions: physical activity-related educational content (i.e., weekly videos, additional resources, easy weekly quiz questions), manual physical activity tracking, and instantaneous graphical feedback. As the physical activity program is goal-directed, these individuals will also receive printed goal setting worksheets.