Inclusion Criteria:  Inclusion criteria: 1) Females or males, aged 18 or older. 2) does not currently engage in 150 minutes of moderate to vigorous PA per week, 3) owns an Android, or iPhone smartphone device, 4) is willing to download a mobile app to be used on the smartphone device, 5) is willing to wear a small, wrist worn fitness tracker for the duration of the study, and 6) is be willing to attend 6 biweekly MI sessions over 12 weeks.  -  Exclusion Criteria:  1) a history of myocardial infarction, angina, coronary artery bypass surgery, congestive heart failure, or diabetes, 2) limiting conditions such as concurrent cancer treatment, peripheral artery disease, orthopedic injury, or pain limiting arthritis, 3) seeking to participate in other structured PA programs during the duration of the study, 4) pregnant at the initiation of the study or plans to become pregnant during the study, and 5) alcohol or other substance abuse within the previous 12 months.  -