Abstract: 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.