Comparing Self-paced Versus Moderate Intensity Physical Activity Recommendation for Midlife Adults

We will randomly assign (blocked on Gender (female, male, other), body mass index (BMI; overweight \[25 \< BMI \< 30\]) or obese (30 \< BMI \<40) and pain status (chronic pain vs not)) adults ages 50-64 into either; (a) self-selected intensity (i.e., SELF-PACED) or (b) prescribed moderate intensity (i.e., PRESCRIBED) conditions. Prior to randomization, persons responding to our ads will participate in the following: (1) telephone screening with the study research assistant (RA) to establish eligibility; (2) an orientation session to obtain more information about the study; and, after providing informed consent (3) baseline assessment and screening (bodyweight, maximal fitness test, dietary intake, and questionnaires to assess potential covariates). Prior to randomization, the RA will give participants an accelerometer to assess baseline physical activity (PA) behavior over a one-week period. Participants will then be randomized to one of the two study conditions. Following randomization, all participants will receive our theory-based PA promotion intervention to help them overcome barriers to regular PA. All participants will be given chest strap heart rate (HR) monitors and instructions on wrist palpation. Follow-up assessments will consist of accelerometry for one-week periods at months 3, 6, 9, and 12, ecological momentary assessment (EMA) throughout the 12 months and bodyweight at 3-month intervals.