Disciple: How do you concentrate on the navel, and why?Sri Chinmoy: You concentrate on the navel because, from there, the life energy can take two courses. If it flows downward, it enters into the lower vital. If it flows upward, it enters into the cosmic energy. In the back of the spine, in the subtle world, are all the chakras. But it is easier to concentrate on the front side of the body. To concentrate on the back of the spine is much more difficult. It is easier to concentrate on the navel than on the corresponding place in the spine. Then repeat 'Supreme' as fast as possible. For purity, the most immediate and effective result comes when you chant outwardly so that the outer ear can hear. But this result is temporary. If you want to have abiding purity, then you have to do it in silence. If you do it outwardly, each time you say 'Supreme,' try to imagine one hundred 'Supremes' inside it, so that your mind feels that you have repeated it hundreds of times. Imagination is a world of reality. Make up your mind that you have done it, and then you will be successful.
Sri Chinmoy, Conversations with the Master, Agni Press, 1977