One thing that helps motivate me to draw near to God more consistently is reading the thoughts of those who have walked with God for many years. Here are a few quotes and insights that have helped me:
My heart has heard you say, "Come talk to me." And my heartresponds, "Lord, I am coming." [Psalm 27:8]
O God, you are my God; I earnestly search for you. My soul thirsts for you; my whole body longs for you in this parched and weary land where there is no water. I have seen you in your sanctuary and gazed upon your power and glory. Your unfailing love is better than life itself; how I praise you! I will praise you as long as I live, lifting up my hands to you in prayer. You satisfy me more than the richest feast. I will praise you with songs of joy. [Psalm 63:1-5]
For my people have done two evil things: They have abandoned me — the fountain of living water. And they have dug for themselves cracked cisterns that can hold no water at all! [Jeremiah 2:13]
Jesus, thou joy of loving hearts, thou fount of life, thou light of men, from the best bless that life imparts ... we turn unfilled to thee again." [Bernard of Clairvaux]
What a friend we have in Jesus, all our sins and griefs to bear; What a privilege to carry everything to God in prayer. O what peace we often forfeit, O what needless pain we bear. All because we do not carry everything to God in prayer. Are we weak and heavy laden, cumbered with a load of care? Precious Savior, still our refuge; take it to the Lord in prayer. Do thy friends despise, forsake thee? Take it to the Lord in prayer; in his arms he'll take and shield thee, thou wilt find a solace there. [Hymn by Joseph Scriven and Charles C. Converse]
If you're looking for a good book on prayer, check out any works by E.M.Bounds. His words are enough to light a bonfire in any cold heart!
Another good book on prayer I've been reading lately is Deepening Your Conversation with God: The Life Changing Power of Prayer by Ben Patterson.