I think modern society, with all of its noise (TV, radio, cell phones, etc.) makes concentration issues exceptionally problematic, and some scientists are even calling the effects a type of technology-induced Attention Deficit Disorder (Read “
The Shallows” by Nicolas Carr for more information about that little phenomenon).
To help quiet your mind, I highly recommend the practice of mental prayer, which is simply to put yourself in the presence of God and think of holy things. There’s a few great methods, described by St. Francis de Sales and by St. Teresa of Avila, but the simple way to do it is to start by sitting in front of a statue, image, or in front of the blessed sacrament if you can. Put yourself in the presence of God by praying to yourself, “I place myself in the presence of the Father, the Son, and the Holy Spirit, present throughout the tabernacles in the world and within me.” Then do a self examination, looking at yourself as God sees you. It’s an act of humility. Then beg for the graces of good prayer, and ask Mary, your guardian angel, and your patron saints to intercede for you that you may have a fruitful audience with God this day. Then pick a topic - the Passion, Heaven, a holy death, Christ as True God and True Man, etc. You may want to pick a book that can help with a topic (I read “Divine Intimacy” during my mental prayer). Then simply sit there, in God’s presence, in the stillness and quietness, and think about Him for 15-30 minutes a day.
This mental break from the chaos of the world, focusing your attention only on God, can be a huge exercise in simply fighting distraction to focus on God. But after a while, and changing a few habits like turning off the TV a few nights a week, or listening to
Audio Sancto homilies in the car instead of the Top 40 station, or simply stopping a few times a day to place yourself in the presence of God and quietly thank Him, your mind will slow down. It may not ever be a perfectly tranquil place, but you can’t have a chaotic life 23 hours of the day and expect to slow your brain down easily for that last hour. My priest says you should not pray that you can live a good life, but you should live so that you can have a good prayer life. Or something like that.