However, the limitations associated with some of the items included within the current study must be acknowledged. First, pain was assessed by a single item at each assessment, and although fatigue-related severity was assessed using four items relating to common experiences of fatigue, fatigue was not included as an item. Second, those items relating to activity limitation required patients to report on their behavior (e.g., are they limiting activity in that moment) and make a judgment relating to that behavior (e.g., is this to control their symptoms), thereby confounding beliefs about symptoms and symptom management with reports of activity. This was a design flaw of the study, which arose because, to provide some comparability with other studies, items from the cognitive– behavioral response questionnaire (a measure of patient activity management) were used. Future studies would benefit from including objective measures of activity, which are separate from measures of patient beliefs about activity. Including pure activity measures would assist us to further develop a theoretical understanding of the dynamic relationships between symptoms and activity. In addition, utilization of mobile-health capabilities, such as incorporating ESM studies alongside established treatment programs, would also enable assessment of the potential mechanisms of change during treatment (Ritterband, Thorndike, Cox, Kovatchev, & Gonder-Frederick, 2009). For example, it would be possible to examine whether hypothesized changes in cognitions are responsible for changes in activity management behaviors (Knoop et al., 2010).