Acharya Prashant explains that before judging an external field, one must first judge oneself. He uses the analogy of a doctor who must diagnose the patient before prescribing medicine. Similarly, one cannot go 'medicine shopping' without knowing their own disease. Therefore, to select a field for oneself, one must first know what is within. This process of self-knowledge should at least run parallel to the exploration of external fields, as one will spend most of their life working. It would be a daily hassle to be in a field where one's heart is not invested. The speaker advises that the process of finding the right path is one of negation, which in Vedanta is called 'Neti Neti' (not this, not this). Instead of asking for the one perfect solution, one should focus on identifying and discarding what is obviously incorrect. This is the way to move forward in life. When a path starts to feel fake, it is time to move on. The tolerance for falsehood should be low because life is short. Addressing the issue of having already invested significant time and resources into a particular path, Acharya Prashant introduces the concept of 'sunk cost'. He warns against the flawed logic of investing more into something just because one has already lost a lot in it. What is lost is a sunk cost and cannot be recovered; investing more will only lead to greater losses. He acknowledges the inner humiliation and ego that makes it difficult to accept past mistakes, especially as one gets older. Therefore, he advises young people to mend their ways and correct their course early, as it is easier for them to accept their mistakes and change direction before it's too late.