If then you were raised with Christ, seek those things which are above, where Christ is, sitting at the right hand of God. Set your mind on things above, not on things on the earth. For you died, and your life is hidden with Christ in God. Colossians 3:1-3 (NKJV)
In Discipline: The Glad Surrender, Elisabeth Elliot writes about the requirements of biblical meditation:
We have been discussing making an offering of the body, which is an act of worship. . . offered by mind and heart. The next thing we are to do is to let our minds be remade and our whole nature transformed.
We cannot do this by ourselves. It is the Holy Spirit who must do the work. But we must open our minds to that work, submit to His control, think on the things that matter rather than on the things that come to nothing in the end. Here again we see both the necessity of a sovereign God working in and through us and the responsibility of the disciple himself to adapt to what God wants to do. . .
In times of prayer and mediation, do not try to think about nothing. “Set your mind,” Paul says, not, “Empty your mind.” Set it on Christ, not on earthly things. One phrase from God’s Word can be taken and repeated quietly, asking that we may be given. . . the spiritual power of wisdom and vision, by which there comes the knowledge of Him.