Web-based Physical Activity Program

The specific aims of the proposed study are: * 1\. To determine if web-based Motivational Interviewing (MI) is effective, compared to an informational web-based comparison group, in enhancing physical activity (PA) participation; and * 2\. To assess the mechanisms by which web-based MI enhances PA through changes in targeted cognitive mediators. The specific hypotheses of the study include that: * Hypothesis 1: Web-based MI will increase PA; * Hypothesis 2: Web-based MI will lead to stage progression in the direction of increased readiness to participate in PA; * Hypothesis 3: Web-based MI will influence theoretically identified cognitive variables; * Hypothesis 4: Cognitive variables will mediate increases in PA participation.