What would it mean to you if you knew that you once lived in the presence of God?
Knowing that God is my Father in Heaven (See Romans 8:16), and that I lived with Him before I came to Earth opens my eyes to help me see what God sees in me. It helps me understand how God knows us all individually, as we all lived with Him for a very long time prior to our existence on earth.
Think of that. God knows you, better than you might know yourself. (See Jeremiah 1:5)
More than that, He loves you, and wants to help you become the best person you can become. That is precisely why he has given us commandments, to lead us in the right way that will help us be happiest.
Knowledge of the pre-mortal existence has helped me grasp what kind of God our Father in Heaven is. He has a physical body, and when we lived with Him, we only had spiritual bodies. Since He is benevolent and loving, He has provided us with this mortal experience to enable us to ennoble ourselves through the application of the atonement of His son Jesus Christ. He did this so that we could gain a body of our own, and learn to choose good over evil.
Now, it is our opportunity to choose the good and come closer to our Father in Heaven with each choice that we make. As His children, let us do what we can so that we might be children He would be proud of. Then, we may truly be "Joint heirs with Christ," (Romans 8:17) and be able to return to live with God again.