J. I. Packer writes in "Knowing God,"
Meditation is the activity of calling to mind, and thinking over, and dwelling on, and applying to oneself, the various things that one knows about the works and ways and purposes and promises of God. It is an activity of holy thought, consciously performed in the presence of God, under the eye of God, by the help of God, as a means of communion with God … It is a matter of talking to oneself about God and oneself; it is, indeed, often a matter of arguing with oneself, reasoning oneself out of moods of doubt and unbelief into a clear apprehension of God’s power and grace.
Packer, J. I. (2011-09-26). Knowing God (p. 22). InterVarsity Press. Kindle Edition.
Christian meditation is not the passive meditation the world seems to enjoy. It is not "let go and let God." Neither is it emptying your mind and letting the Holy Spirit reveal truth to you.
Meditation is work. It takes effort. And it results in spiritual growth and depth, as nothing else will.