If I could go back, I'd have done this. I'd have chosen this other thing. I'd have worked harder, and I'd have hung out more. Many of the things I wished I'd have done in the past are, in fact, irreconcilable with each other: I wish simultaneously to have had more rest and to have had more nights out. It is easy to think about how our lives would be better if we had done this other thing or chosen this other path. Paradoxically, we are incredibly optimistic when thinking about the 'what would've been' , and yet very risk-averse in the present moment: I forget about the trade-offs I considered back then on today's regrets. Yet these trade-offs come back -as it is natural- in our everyday decision-making, in our everyday building of the future. There's even a term for this: hindsight bias. ...