When I was a little kid, my mother told us: “You are what you eat!”. If you eat junk food your health will be junk, if you eat healthy foods you will be healthy. But are we really defined by what we eat? Absolutely not! Do you know what we really are? The answer is: You are what you think about most of the time. If you think about material things you are a material person. But if think about Torah and Kedusha you are Holy, you are a real Authentic, Torah Jew.
Rabbi Avigdor Miller ZATZAL said often that if you want our Creator to “think about” you, you must make it your business to “Think about Him“. We absolutely must think about HASHEM and His Torah as much as we can.
We must take control of our thoughts and mental images. We are responsible for what we think and dream about. If we flood our mind’s eye with images of Torah and Kedushah (like thinking about great Tzadikim or seeing ourselves overcoming challenges the Yetzer Harah puts to us etc.) we will indeed become pure and lofty.
So: You are what you think about! Your brain (mind) is a very powerful tool. Let’s use it in HASHEM’s service!