Now, I know this advice isn’t going to have any effect on you, but I’ll tell you anyway to answer the question. If you can train yourself to think for five minutes on one subject you’ll be amazed at the transformation it will create in you. You’ll start drawing from the depths of your mind such a wealth of chochmah that you’ll be surprised that you were capable of it. And every human being has that in his mind. L’havdil, the story is told of Euclid. He invented the rules of geometry. He used to take a lowly, uneducated slave and ask him questions, and by his questions he caused the slave little by little to come up with the right answers. Finally, the slave enunciated all the principles of geometry. It’s logic. Geometry is logic. And it lodges — it’s buried — very deep in every man’s mind. Now, there’s much more wisdom than geometry, and we have the potential to bring it forth. But people are too lazy. They want to think superficially. But if you want, this is one of the ways to do it. Sit for five minutes — not only once in your life, but frequently — and concentrate on one subject.
Astor, Yaakov. Rav Avigdor Miller on Olam Haba (pp. 140-141). The Judaica Press, Inc.. Kindle Edition.