RecruitingBehavioural interventionAcceptance and Commitment Therapy to Improve Disability in Chronic MigraineThe goal of this clinical trial is to learn if the behavioral treatment called Acceptance and Commitment Therapy (ACT) works to improve disability in adults with chronic migraine. The main questions it aims to answer are: Does the use of ACT added to usual treatment improve scores on questionnaires designed to measure daily functioning and activity? Does the use of ACT added to usual treatment improve scores on diaries designed to measure headache frequency and pain? Researchers will compare adding ACT to usual headache treatments to usual headache treatments without ACT. Participants who are selected for ACT will take 8 classes to learn ACT and then will practice it at home, in addition to their regular headache treatment. Those not selected will continue their regular headache treatment. Four times over the following year, participants will answer questions about their symptoms during each of four virtual visits. They will also keep a daily headache diary during the study