Forming an implementation intention or “if-then plan” promotes the attainment of different types of goals (Gollwitzer, 1999; Gollwitzer & Sheeran, 2006). So far, research on implementation intentions has focused on the initiation of goal striving, whereas the issue of shielding of ongoing goal striving has been largely neglected. In two field experiments concerned with dieting (Study 1) and athletic goals (Study 2), goal shielding was supported by implementation intentions geared at controlling potentially interfering inner states (i.e., cravings for junk food in Study 1, and disruptive thoughts, feelings, and physiological states in Study 2). In both experiments, forming ifthen plans enhanced the rate of goal attainment. Thus, implementation intention formation can be used to promote the realization of desired outcomes not only by facilitating getting started with goal striving but also by preventing goal striving from straying off course.