Although we know better, we delay activities, often with negative consequences. College students know it all too well; they have to write a term paper in several weeks, but only start studying for the exam a week before. Instead of doing our laundry, we watch YouTube videos for another hour. The curious thing is that we do all this despite its negative consequences. Procrastination is an irrational behavior. Yet, it is widespread. But why are we so bad at self-regulating ourselves? To better understand this irrational behavior I wrote a simulation based on the Temporal Motivation Theory by Piers Steel. Find the result here.