In the past, there was a master who contemplated, “What is the original face before my parents were born?” He contemplated for many years but did not awaken. Later, he encountered a great noble person and requested compassionate guidance.

The noble one asked, “What koan did you contemplate?”

He replied, “I contemplated: what is the original face before my parents were born?”

The noble one replied, “You contemplated too far away. You should look nearby.”

He asked, “How should I look nearby?”

The noble one replied, “Do not look into what is before your parents were born. Instead, look at this: before a thought arises, what is it?”

The Zen practitioner immediately attained great awakening.

Everyone sitting here, please look: before a moment of thought arises, what is this? It is radiating light in front of everybody’s sense doors. Its brightness illuminates everything, yet it is without the slightest clinging. Nothing is known and nothing is seen, yet it is not like wood and stones. What is this?

It is right here, shining in its brilliance. This is awakening to the Way. Therefore it is said, “The great Way is not difficult; just cease speech and words!”

- Yuan Yin Lao Ren

The knee-jerk answer for many people, when asked what they are before thinking, is: “Oh, nothing.”

But you are clearly not a void or nothingness. You are clearly still conscious, present, existing, and aware. What exactly is that?

If thought says, “Oh, Awareness!” that is just another thought — and again, precisely not what you are.

So you keep investigating, non-verbally, what you actually are before all words, definitions, thoughts, and labels. Before all conceivable and perceivable phenomena, what are you actually?

This is also helpful:

What is your very Mind right now?

Do read it in its entirety.