Knee osteoarthritis (KOA) is one of the most common causes of chronic pain, mobility problems, and disability among United States Veterans. Many Veterans with KOA also experience depressive symptoms, which can worsen pain, reduce motivation to exercise, and make recovery more difficult. This study will test whether a structured hybrid aerobic exercise program that combines supervised and home-based walking with the medication duloxetine can improve physical function, reduce pain, lessen depressive symptoms, and improve overall health-related outcomes in Veterans with KOA. The goal of this research is to develop a practical and scalable treatment strategy that could improve rehabilitation and quality of life for Veterans with chronic knee pain and depressive symptoms and potentially be adapted for other chronic musculoskeletal conditions treated within the VA healthcare system.