Patients with asthma and chronic obstructive pulmonary disease (COPD) often experience anxiety and depression in relation to their respiratory condition. Anxiety and depression in this population are associated with decreased activity. The aim of this phenomenological study was to carry out in-depth qualitative interviews with a purposive sample of patients with asthma and COPD taking part in an 8-week mindfulness-based cognitive therapy (MBCT) course to explore their experiences of MBCT. In particular, we were interested in how the mindfulness approach helped them, or not, and their awareness of any meaningful changes in relation to their breathlessness, activity levels, anxiety or low mood. Twenty-two patients were recruited from primary and secondary care to receive an 8-week course in MBCT. Two groups of MBCT were taught by qualified MBCT teachers in a community setting. Of the 22 patients who attended the MBCT course, 12 patients were purposively sampled to take part in an in-depth qualitative interview 2 months after completing the MBCT course. Interviews were digitally recorded and transcribed verbatim. Analysis was thematic. The themes that emerged included greater acceptance and reduced sense of disease-related stigma; noticing subtle bodily sensations to detect early warning signs of breathlessness; linking pulmonary rehabilitation advice with mindfulness; developing a new relationship to breathing, activity and associated thoughts; having a greater sense of control; being creative around limitations and removing psychological barriers to being more active. Findings offer, for the first time, qualitative evidence on how MBCT benefits patients with asthma and COPD who experience anxiety and depression. These data provide a useful adjunct to existing quantitative evidence in this area.