With input from patients, family members, and clinicians, the Investigators have designed a study to address this gap and propose a clinical trial that will compare the effectiveness of MM to standard-of-care CBT in opioid-treated CLBP. Based on the existing research, it is hypothesized that MM training will lead to a larger reduction in pain intensity, increase in physical function, improvement in quality of life, and decrease in daily opioid dose, as compared to CBT training, with benefits of MM especially notable in adults with worse mood, anxiety or unhealthy opioid-use behaviors who often experience more severe symptoms of CLBP and less improvement in response to existing therapies.