Acharya Prashant explains that the only way to be sure of one's path in life is to test it through active inquiry and experimentation rather than relying on blind belief. He emphasizes that life is a unique experience for every individual, and one must apply intelligence to verify if a chosen direction is correct. He compares life to mathematics, noting that one cannot simply claim a solution is proven without doing the requisite hard work and solving the problem. Drawing premature conclusions without understanding the underlying issues leads to failure, which he describes as receiving a zero from life.