Patients with asthma engage in less physical activity than peers because of concern about exacerbating respiratory symptoms. The randomized trial by Mancuso et al attempted to increase lifestyle physical activity, primarily walking, in 258 New York City primary care patients with asthma over 12 months by applying several tenets of health behavior theory. Patients randomized to the control group received a multicomponent protocol consisting of making a contract to participate in a specific physical activity, increasing knowledge of exercise and asthma, using a pedometer, and receiving telephone reinforcement. Patients randomized to the intervention group received these same components and were also taught techniques to increase positive affect and self-affirmation that were linked to the physical activity. After 12 months, energy expenditure measured by self-report increased by 415 kcal/wk (95% CI, 76-754; P = .02) in controls and 398 kcal/wk (95% CI, 145-652; P = .002) in intervention patients, with no difference between groups. For both groups, this increase exceeded a clinically important difference. No adverse events were attributed to the trial. At close-out, asthma-related quality of life stayed the same or improved in 81% of patients.