What is it in us that calls out desire?  Look into your own mind, and you will find that memory and imagination are the two things that evoke desire most strongly.  Hence thought is the means whereby all the changes in desire can be brought about.  Thought, imagination, is the only creative power in you, and by imagination your powers are to be unfolded.  The more you think of a desirable object, the stronger becomes the desire for it.  Then think of Yoga as desirable, if you want to desire Yoga.  Think about the results of Yoga and what it means for the world when you have become a yogi, and you will find your desire becoming stronger and stronger.  For it is only by thought that you can manage desire.  You can do nothing with it by itself.  You want the thing, or you do not want it, and within the limits of the desire nature you are helpless in its grasp.  As just said, you cannot change desire by desire.  You must go into another region of your being, the region of thought, and by thought you can make yourself desire or not desire, exactly as you like, if only you will use the right means, and those means, after all, are fairly simple.  Why is it you desire to possess a thing?  Because you think it will make you happier.  But suppose you know by past experience that in the long run it does not make you happier, but brings you sorrow, trouble, distress.  You have at once, ready to your hands, the way to get rid of that desire.  Think of the ultimate results.  Let your mind dwell carefully on all the painful things.  Jump over the momentary pleasure, and fix your thought steadily on the pain which follows the gratification of that desire.  And when you have done that for a month or so, the very sight of those objects of desire will repel you.  You will have associated it in your mind with suffering, and will recoil from it instinctively.  You will not want it.  You have changed the want, and have changed it by your power of imagination.  There is no more effective way of destroying a vice than by deliberately picturing the ultimate results of its indulgence.  Persuade a young man who is inclined to be profligate to keep in his mind the image of an old profligate; show him the profligate worn out, desiring without the power to gratify; and if you can get him to think in that way, unconsciously he will begin to shrink from that which before attracted him; the very hideousness of the results frightens away the man from clinging to the object of desire.  And the would-be yogi has to use his thought to mark out the desires he will permit, and the desires that he is determined to slay.

The next thing after a strong desire is a strong will.  Will is desire. transmuted, its directing is changed from without to within.  If your will is weak, you must strengthen it.  Deal with it as you do with other weak things:  strengthen it by practice.  If a boy knows that he has weak arms, he says:  “My arms are weak, but I shall practice gymnastics, work on the parallel bars:  thus my arms. will grow strong.”  It is the same with the will.  Practice will make strong the little, weak will that you have at present.