You're realizing that entering into the silence before God which is prayer awakens a riot in your brain. Thoughts and images come from all over to distract you. You might fight them off or drown out the noise by focusing on a text of Scripture or using words for your prayers. And that's not a bad path, but it won't bring you ultimately into the presence of God where you must be absolutely still and enter the silence which is the language of God (see the Bible's story about the Mount of Transfiguration). So, today, enter the stillness of prayer and as you do, watch the thoughts your ego parades through your mind. Get some distance from this riot of sight and sound. Treat your thoughts like movie images cast upon the screen in the theater of your brain. Sit down with your popcorn in a seat half way up. Before you know it, you'll be sucked in, plastered to the screen itself, fully identified with what's taking place there. When you are, peel yourself off the screen, and troop back to your seat and sit down again and watch your thoughts. You'll get pulled out of your seat again and again and again.
Be kind to yourself. This isn't easy work. Again and again, take up your seat a good distance from the images on the screen of your mind and watch them until you get a little distance between the you who watches the thoughts and the self who thinks them.
You're on your way to "taking every thought captive to make it obey Christ," the Beloved, who is the source and goal of all prayer (2 Corinthians 10.5).