Rav Avigdor Miller on Avinu Malkeinu
Q:
How can we come to realize that Hashem is our father?

A:
Now I’ll tell you a queer thing, but this is how to do it. If you’ll stand in a corner when nobody is around and you’ll say “Avinu” – Our Father. Say it again and again. “Avinu, Avinu, Avinu.” Say it a hundred times. And it’s going to sink in after a while that He’s really your father.

That’s not the only way, but that’s a very effective way. And this we learn from Reb Yisrael Salanter, zichrono livracha. He taught us that we have to repeat the great ideas. You have to say these words over and over and listen to what you’re saying; and in the course of time it’s going to sink in. If you mean business, that’s the way to say it. Now, if you’ll always think about what you’re saying when you say the word Avinu in the tefillos – if you’ll think what this word means, “Our Father” – then it’s going to help too. Only that during davening people are usually in such a hurry that they don’t stop to think.