Just as the body becomes exhausted and overloaded with activity, so does the mind. If we don’t take time to clear out some of the clutter, big problems will develop. Sleep is one way to do this. Meditation is another.
Meditation is not a one size fits all type of thing. There are many different forms of meditation practice.
Many Christians have been warned of the evils of meditation. There are a variety of forms of Christian meditation and centering prayer available. A mantra is simply used to help you focus, it does not have to be OM. I begin by surrounding myself with the white light of God’s love and protection, focus on my breath going in and out and silently repeat a favorite scripture, or “God is love, God is Joy, God is peace.” You will also get benefit from progressive relaxation exercises if that is more comfortable for you. If you want scriptures supporting meditation look up Psalm 1:2, 46:10, 91:1, I Kings 19:11-12.
Find a practice that is a good fit for you and get started. It doesn’t take long to see benefits, but can be a little overwhelming for a beginner. Seek out a teacher or meditation group for help if needed.