RecruitingBehavioural interventionOptimizing a Remote-based Physical Activity Intervention for Adults With Total Knee ReplacementThe purpose of this study is to identify which supplemental intervention components added to an online exercise program contribute to the greatest increases in physical activity (total MVPA and percent meeting guidelines \[≥150 min/week of MVPA\]) in adults with knee replacement at 6 and 12 months. Secondary outcomes will examine changes in pain and physical function.