Rationality is the martial art of the mind, building on universally human machinery. But developing rationality is more difficult than developing physical martial arts. One reason is because rationality skill is harder to verify. In recent decades, scientific fields like heuristics and biases, Bayesian probability theory, evolutionary psychology, and social psychology have given us a theoretical body of work on which to build such a martial art. It remains to develop and especially to communicate techniques that apply this theoretical work introspectively to our own minds.
Why should we seek truth? Pure curiosity is an emotion, but not therefore irrational. Instrumental value is another reason, with the advantage of giving an outside verification criterion. A third reason is conceiving of truth as a moral duty, but this might invite moralizing about "proper" modes of thinking that don't work. Still, we need to figure out how to think properly. That means avoiding biases, for which see the next post.
Biases are one kind of obstacle to finding truth.