When pursuing a goal, making a backup plan has many benefits, including reducing the psychological discomfort associated with uncertainty. However, we suggest that making a backup plan can also have negative effects. Specifically, we propose that the mere act of thinking through a backup plan can reduce performance on your primary goal by decreasing your desire for goal achievement. In three experimental studies, we find that individuals randomly assigned to think through a backup plan subsequently performed worse on their primary goal (Studies 1–3). We further show that this effect is mediated by study participants’ decreased desire to attain their primary goal (Study 3). This research provides a fresh perspective on plan-making, highlighting an important yet previously unexplored negative consequence of formulating plans.