Seeking the truth is the unending pursuit of uncovering reality.
People only see what they want to see, believe they want to believe. And so, people deceive themselves and live in fantasy. The truth is based on reality, not on a dream.
In seeking the truth, you stop deceiving yourself. You stop protecting your ego, and you stop persuading others that you are right.
To become a truth seeker, you cannot fully accept the "truth" of an expert or a person of authority.
Go beyond and find it yourself. See it, and hear it. Taste it, and feel it. Even then, you cannot trust your senses entirely. The Yanny/Laurel and the blue/black or white/gold dress proves we cannot trust our senses.
Go further and look for people. Look for people with the same experiences, for they confirm commonality. Look for people with different backgrounds, for they confirm uniqueness. Look for people without the experience, for they confirm specificity.
Keep going and look for data. Collect, record and measure these experiences. Find patterns, anomalies, gaps and movements.
Even then, the path continues further still. Til one day, you encounter the truth. When you look back at your truth-seeking journey, it will all be worth it.