Stadler et al., 2009: Reflecting, planning, and setting goals doubled physical activity among women over four months
Women in two groups both received information about the benefits of exercise. Those in the “mental contrasting + implementation intentions” group also wrote down “(1) their most important current wish regarding physical activity (e.g., biking to work); (2) the most positive outcome of realizing their wish (e.g., getting into better shape) and events and experiences they associated with this positive outcome; (3) the most critical obstacle (e.g., getting up too late) together with events and experiences they associated with this obstacle; and (4) three implementation intentions with the following questions: (1) When and where does the obstacle occur, and what can I do to overcome or circumvent the obstacle?; (2) When and where is an opportunity to prevent the obstacle from occurring, and what can I do to prevent it from occurring?; and (3) When and where is a good opportunity for me to act on my wish, and what would this action be?”. Participants in the latter group were twice as physically active as participants in the former group (1 hour more per week) over the course of a 4-month follow-up period.