Thinking with own mind is one of the most powerful tools human being possesses in order to carry out its existance. Based on this, it is important to split how humans can think in two different ways, the rational and irrational. When we talk about rational feelings, we consider every action people do in every daily life, such as in a work place, the second one is related to an instinctive behaviour of the human being, such as anxiety, love and so on. In this essay I want to highlight how intelligence is deeply related to thinking, both rational and irrational, and thus create the starting point for success.