Additional Study Information: Capnography-Assisted, Learned, Monitored (CALM) Breathing is a mind-body intervention for COPD that uses breathing exercises and biofeedback with the goal of reducing shortness of breath, anxiety symptoms and improving overall quality of life. The intervention is a 4-week (1 hour, twice weekly) program taking place in-person at New York Presbyterian Hospital and Columbia University Irving Medical Center. The breathing therapy is implemented before pulmonary rehabilitation. Eligibility criteria include a COPD diagnosis, supplemental oxygen use less than 8 hours per day, ability to read, write and speak English, and ability to maintain oxygen saturation of 90% at room air.