Behavioral Activation Teletherapy to Increase Physical Activity

Inclusion Criteria: * Be18-64 years old; * Able and willing to provide informed consent; * Have moderate-to-severe depressive symptoms, with a PHQ-9 score ≥ 10; * Insufficient moderate-to-vigorous physical activity (\< 90 minutes a week); * Demonstrated interest in increasing physical activity; * Have a smartphone. Exclusion Criteria: * Have any current, past, or lifetime manic or hypomanic episode, psychosis, schizophrenia or schizophreniform disorder; * Be currently experiencing active suicidal ideation (i.e. with suicidal thoughts, plan, and intent) or at a high risk for suicide during the course of the study, as designated by the PI; * Have a medical condition that prohibits physical activity; be medically prohibited to exercise by primary care physician (PCP), OB-GYN (obstetrician-gynecologist) or study MD. * Be in current, active psychotherapy