Assessment of the Predictors and Moderators of Health Behavior Change

This intervention will incorporate elements from several widely established self-regulatory strategies aimed at enhancing the motivational aspects of goal pursuit, including mental contrasting (Oettingen, 2000), self-reflection (Koestner et al., 2002), self-affirmation (Schmeichel and Vohs, 2009), and the values clarification components of Acceptance and Commitment Therapy (ACT; Hayes, Strosahl, \& Wilson, 1999). Participants will be prompted to enter their selected health goal and will then be instructed to identify personal values that might be practiced in pursuit of this goal. Participants will write about these values for several minutes, after which they will be instructed to select a short phrase or image that conjures up for them the reasons they choose to engage in their goal. Participants will be asked to type the phrase into a textbox and will have the option of receiving a confidential print-out of their chosen phrase at the end of the study visit.

"Participants in this condition will be guided to create detailed implementation intentions, or if-then planning statements (Gollwitzer \& Sheeran, 2006), specifying when, how, and where they will engage in their selected health goal. Participants will be provided with a detailed rationale adapted from earlier research on implementation intentions (e.g., Webb et al., 2010). Participants will be guided to generate a plan indicating when, where, and how they will enact their goal-based behavior over the next week. They will also be prompted to identify 3 obstacles they are likely to encounter during the pursuit of each goal, and to specify in an if-then format what specific actions they will take to overcome each obstacle (following the procedures and sample if-then responses of Koestner et al., 2002). They will be asked to rehearse each if-then statement to themselves before the end of the visit."

"Participants in this condition will complete abbreviated versions of both the values clarification and planning procedures, as detailed above. Participants will be prompted to identify 2 obstacles (as opposed to 3) they might encounter during the pursuit of each goal. For each of the obstacles they identify with respect to each of their target goals, they will be prompted to form an additional implementation intention in the form: When \[I encounter the specified obstacle\], I will do \[X\] and remember \[values-based statement or image identified during values clarification exercise\]. They will be asked to rehearse these if-then statements to themselves before the end of the visit."