The present research investigated whether asking ‘‘why’’ concerning the pursuit of one goal can affect the subsequent pursuit of a previously chosen goal. Asking ‘‘why’’ should activate cognitive procedures involving deliberation over the pros and cons of a goal (why-mindset). This mode of thinking should spill over to subsequently pursued goals, with different consequences for goal striving guided by goal intentions and for goal striving guided by implementation intentions (if-then plans). As goal intentions guide behavior by effortful top-down action control processes motivated by the expected value of the desired outcomes, being in a why-mindset should induce defensive postdecisional deliberation and thereby promote goal pursuit. In contrast, implementation intentions guide behavior by automatic bottom-up action control processes triggered by the specified situational cues; in this case, being in a why-mindset should eliminate the effects implementation intentions have on goal pursuit. Performance on a handgrip self-control task (Study 1) as well as on a dual-task (simultaneous go/no-go task and tracking tasks; Study 2) supported these predictions: why-mindsets reinforced goal intention effects and impaired implementation intention effects on handgrip and dual-task performance. Implications for effective goal striving are discussed.