In this verse, Moses answers a question that persists to this day: When did God begin? In brief, He did not "begin;" He has always existed and will always exist. The existence of God is eternal, without beginning or end. Prior to the formation of the mountains and the creation of the earth and universe, God lived. Without this, there would not be anything at all.
In Genesis, we are told about the beginning of creation. There was only God before time space and matter were created, before the universe existed, and before man was created in His image and likeness. Infinite and eternal is God, and He will remain so forever. The Psalmist attempts to explain this concept, which is incomprehensible to mankind.
In eternity, God is unchanging. There is no beginning or end to Him. He is the first and the last. Everything that exists and everything that will exist has its origins in Him. Neither men nor angels are necessary to complete him, and He is sufficient in Himself. In His sublime glory and in His great majesty, He exists. In Himself, He is self-sufficient, self-sustaining, and all-inclusive.

Dear Heavenly Father, there is great comfort in knowing that I cannot be anywhere or at any time without You. Through Your Spirit, please encourage me to be braver in sharing the Gospel of Jesus through Your power and presence. Though I am unable to comprehend the wonders of Your existence, I praise Your name that You have revealed Yourself to me. Help me to get to know You better, to love You better, and to follow You closer every day. 
In Jesus's name I pray. Amen.