This little exercise is not meant to trivialize our time with God or say that we can cram in a relationship with him in just a few minutes a day. Rather, it is meant to get us into a thankful frame of mind so we can look for God's involvement in all we do, in everyone we meet, and in every circumstance we encounter.
As you commute to work, go through the alphabet and praise God, starting with each letter. If verses come to mind, include those in your prayers. When you get to Z your 15 minutes is up. Now begin to pray for the things, people, and situations you care about. Finish by saying, "Speak to me, Lord, and help me to listen and obey." Try to remain silent and listen. Finally, feel free to add your own words as you go through the alphabet. This is your prayer and praise time with God. Enjoy!