This practice cannot be done if one has not completed pratyahar sensual energy close-down. And that practice takes years to complete.

Some student get the hair-brained idea that they can master these practices in a jiffy but it is like the growth of the body, from the infant stage.

Suppose a child hears that he should grow himself/herself to become an adult. Can he/she do that in two years. We notice that no matter how much a child stuffs still the body only grows at a certain rate whereby it takes years for it to reach adult stage.

The effort to eat healthy food must be made, but that does not change the rate of growth which is already preset by Nature's biology.