Jonah Lehrer’s book examines and presents decision-making processes through practical examples. The essential questions of the book are the following: ‘How is the human mind deciding? And how can I improve these decisions?’ (Lehrer, 2012). Decision-making mechanisms define our everyday lives. This is valid for our workplace as well as for our private life too. Scientists believe in the rational brain for centuries. In various disciplines, unanimous decisions based on sheer rationality alone is considered to be correct and acceptable. The book of Lehrer gives a much more sophisticated picture of the decision-making mechanism of the human brain. Enlightening that some brain areas developed during evolution, how they contribute to each decision-making processes. Practical examples illustrate the relationship between emotions and rationality during decision-making.