Sedentary behavior is a risk factor for heart disease, independent of meeting physical activity guidelines. Tweet4Wellness is an innovative light physical activity, specifically walking, intervention which randomly assigns participants to a 25-person private, online support group that will receive daily, theory-based messages as peer-to-peer discussion prompts. Many text-based interventions do not base the intervention text messages in behavior change theory, but this study will base the daily messages in the behavior change theories such as implementation intentions, social support, mindfulness, and social learning theory.