Type 2 diabetes (T2D) is associated with considerable functional impairment and reduced quality of life. Consistent daily engagement in self-management behaviors, such as physical activity, medication adherence, and monitoring blood glucose is required to maintain daily functioning, quality of life, and glucose control. However, most Veterans do not meet daily self-management targets, particularly physical activity. This is problematic as physical activity is a cornerstone of T2D self-management and represents a fundamental component of functioning. Self-management occurs in the context of patients’ own environments. Thus, assessments at healthcare visits likely miss significant amounts of variability in self-management behaviors as well as daily fluctuations in comorbid symptoms and social contextual factors that influence self-management. The conceptual model guiding the proposal is based on temporal self-regulation theory and posits that because T2D is generally asymptomatic, consequences of poor self-management and benefits of consistent self-management are not salient in the moment. For Veterans with T2D, comorbid symptoms such as mood, pain, and stress are common time-varying momentary barriers to self-management that may particularly impact physical activity. Social context is another well-established set of factors related to self-management among people with T2D. Most research on barriers and facilitators of T2D self-management is cross-sectional and assumes comorbid symptoms and contextual factors are static. Current research does not address the time-varying nature in which these comorbid symptoms and social contextual factors impact physical activity and other self-management behaviors within individuals. Thus, the overarching aim of the current proposal is to understand daily, time-varying factors (comorbid symptoms, social context) that are particularly relevant to Veterans and that influence physical activity, T2D self-management, daily functioning, and quality of life. We will enroll 95 (5 test participants and 90 for the analytic sample) Veterans with T2D and will use ecological momentary assessment (EMA), a method of real-time data collection. Participants will receive 5 momentary EMA surveys and 1 daily EMA survey per day, in which Veterans will report on comorbid symptoms (mood, stress, pain, PTSD), social support, social interactions, physical activity and other self- management behaviors, randomly, during pre-programmed intervals in their natural environment over a 14-day sampling period. Accelerometry will also assess physical activity. With these data, we will address 4 aims: Aim 1) Use EMA to examine within-person time-varying relationships among daily comorbid symptoms (depressed mood, stress, pain, PTSD) and within-day time spent doing physical activities; Aim 2) Use EMA to examine within-person social contextual factors (social support, social interactions) and daily time spent doing physical activities; Exploratory ...