An inability to be guided by a “healthy fear” of bad consequences is a disastrous flaw. - Daniel Kahneman

The nervous system consumes more glucose than most other parts of the body, and effortful mental activity appears to be especially expensive in the currency of glucose.

a stable relationship requires that good interactions outnumber bad interactions by at least 5 to 1.

When forecasting the outcomes of risky projects, executives too easily fall victim to the planning fallacy. In its grip, they make decisions based on delusional optimism rather than on a rational weighting of gains, losses, and probabilities. They overestimate benefits and underestimate costs. They spin scenarios of success while overlooking the potential for mistakes and miscalculations. As a result, they pursue initiatives that are unlikely to come in on budget or on time or to deliver the expected returns — or even to be completed. In this view, people often (but not always) take on risky projects because they are overly optimistic about the odds they face. I will return to this idea several times in this book — it probably contributes to an explanation of why people litigate, why they start wars, and why they open small businesses.