Empowered Relief and Exercise Rehabilitation for People With Subacromial Shoulder Pain

The goal of this clinical trial is to learn whether a single 2-hour online pain skills session called Empowered Relief can help adults with subacromial shoulder pain who are taking part in a 12-week exercise program. The main questions it aims to answer are: * Does Empowered Relief lower unhelpful thoughts and beliefs about pain? * Does Empowered Relief help participants complete more of their prescribed exercises? All participants will receive the same 12-week exercise program and the Empowered Relief session. The timing of the Empowered Relief session will be randomly assigned between day 10 and day 26 after starting the exercise program. This allows researchers to compare each participant's responses before and after the session. Participants will: * Follow a 12-week home exercise program for their shoulder. * Take part in one 2-hour online Empowered Relief session. * Answer brief daily questions for 12 weeks about their thoughts about pain, what they expect to feel during exercise, what they actually feel after exercise, and how much of their exercise program they complete. * Answer brief weekly questions after their Empowered Relief session about their use of the strategies taught in the session. * Complete longer questionnaires at the start of the study and after 4, 8, and 12 weeks.