Cognitive scientists tell us that we are hardwired for deception. It seems we are overly optimistic, and, in fact, we wouldn't have survived without this trait. With this built-in bias as a starting point, it's almost impossible for us to estimate accurately. That doesn't mean all is lost. We must simply accept that our estimates are best guesses and continually re-evaluate as we go, which is, of course, the agile approach to managing change. Linda Rising has been part of many plan-driven development projects where sincere, honest people with integrity wanted to make the best estimates possible and used many "scientific" approaches to make it happen-all for naught. Re-estimation was regarded as an admission of failure to do the best up-front estimate and resulted in a lot of overhead and meetings to try to "get it right." Offering examples from ordinary life-especially from the way people eat and drink-Linda demonstrates how hard it is for us to see our poor estimating skills and helps us learn to avoid the self-deception that is hardwired in all of us.