<qa>  What is the primary aim of the 8 week yoga program for CF patients?The investigators hypothesize that yoga will be an activity that is safe and tolerable for CF patients 12 to 25 years of age. The primary aim is to investigate the safety and tolerability of an 8 week yoga program for patients with CF. The secondary aim is to determine the effect of yoga on many aspects of CF disease including respiratory symptoms, adherence to regular CF therapies, quality of life, lung function, exercise tolerance, and nutritional status. 