The Psychology of "I’ll Do It Later" (And How to Hack It) If 95% of people agree that donating blood is a "good thing," why do only 3% actually do it? Economists call this the Intention-Behavior Gap. It is the chasm between who we want to be (heroes) and who we actually are (people who hate needles). This gap isn't because you are lazy or uncaring. It is because your brain has a few evolutionary "bugs" that prevent you from acting.