The impact of impact

"For example, the Duke psychology professor Dan Ariely and colleagues conducted a study in which participants were paid to build Lego models, some of which were dismantled in front of them upon completion. People whose creations were preserved made, on average, 50% more Lego models than those whose models were destroyed, despite identical monetary incentives. We give more of ourselves when we have an impact - even if it's a small one."

-- via Harvard Business Review