It should be noted that subjects were encouraged to increase their MVPA to meet national PA guidelines, but instead they increased their LPA. The lack of an increase in MVPA is likely explained by two factors. It is possible that subjects overestimated the intensity of their PA and this is supported by their self-report of 68–87 minutes of exercise a week compared with objective measures of 5±5 minutes/day of MVPA at entry into the study. They thought they were exercising at a moderate-to-vigorous intensity, but in fact they were only exercising at a light intensity. Additionally, it could be explained by their pulmonary symptoms and an inability to sustain higher volumes of MVPA on a day-to-day basis.