You've already taken the first step by recognizing that you have this problem. Many people, I'm afraid, approach worship casually, and never experience the joy of worshipping God as they should.
Have you ever asked yourself what worship is? True worship takes place only when our full attention is on God -- on His glory, His power, His majesty, His love, His compassion. This doesn't happen easily; even in church or in our times of private devotion we can get distracted and fail to see God as He truly is. The Bible says, "Come, let us bow down in worship, let us kneel before the Lord our Maker; for he is our God and we are the people of his pasture, the flock under his care" (Psalm 95:6-7).
How can we worship God? First, take time to prepare for worship. We rush off to church or hurry through our devotions -- and then we wonder why God seems so distant. Prepare your heart in advance, and bow for a few moments of prayer before your church's service begins.
Then ask God to help you focus on who He is and what He has done for you. God created you; He also sent His Son into the world to redeem you. Turn your mind and heart to Him every day, praising Him for who He is and thanking Him for His love for you in Christ.