Those two words, spoken by Jesus, have changed the world. "Our Father..."
Before he gave his disciples freedom to speak directly to God, they prayed quite differently. They followed strict rituals, they brought their petitions to the priest, and he prayed on their behalf. He kept his eyes averted, and never directly addressed God by name. The Jewish people didn't even have a name for God, they gave Him the unpronounceable YHWH. We, of course, added a few vowels and use the word "Yahweh" as one of the names we call our Father.
With these two words, "our Father", we could now pray directly to God, and on behalf of others.
It has been suggested that how we relate to our own fathers conditions us in the manner in which we relate to God. For some He is authoritarian and strict, for others a friendly daddy.
The first few sentences of the Lord's Prayer are addressed vertically, directly to God. We recognize His place in our lives. We pay tribute, and then we move on to petitions.
The petitions are a horizontal expression of our oneness as a people. Give us this day OUR daily bread, forgive us OUR trespasses, and so on. This prayer is meant to be prayed daily, if not for ourselves, for others. Our DAILY bread, not "enough bread until I get around to praying again," but our daily bread.
The Holy Spirit, breathed into the world by God when He sent the Word, His Son, in the same way that when we speak our words they are sent out with our own breath. The Holy Spirit gives us the courage and faith to pray the Lord's Prayer daily. The Lord's Prayer is perhaps the most profound statement of our belief in the Triune God; the Father, the Son and the Holy Spirit, and we say it daily separately and together.