To concentrate effectively, establish your attention on a form that gives you joy. Sit in the padmasana (lotus) posture and fix your eyes on the tip of your nose. In the beginning, practice meditation for a minute; then for three minutes. A few days later try for six minutes and after some time, for as long as nine minutes. Thus the concentration has to be strengthened gradually, without undue hurry. Slowly the mind can be held for even half an hour; this discipline must be developed steadily. With practice, the mind will get fixed and the power of concentration will increase. To attain concentration and acquire one-pointedness, you must undergo exertion to some extent. You must fasten your mind on the Lord and keep off all other thoughts from the mental plane. By such exercise done constantly, your vision will be firmly fixed on the Lord residing in your heart . That is, verily, the goal, the full fruition of meditation.
- Dhyana Vahini, Ch 13: “Developing One-pointedness”