Your body is made of two things: your will to do, your....

“ Your body is made of two things: your will to do, your ego, and the physical form you have received from the prakriti, the nature. If the will to do is present within you, then the nature will go on providing you with an appropriate body. This is how you have been born again and again. Sometimes you were an animal, sometimes a bird, a tree some other time, and sometimes a man. Whatsoever you wished to achieve, it has happened. Your desire to achieve becomes the actuality; thoughts become real things. So beware when you desire, because all desires are fulfilled – sooner or later.If you are of the habit of watching the birds fly in the sky and wonder, ”How free the birds are, I wish I were a bird.” it will not be long before you become a bird. You see dogs mating, and if that moment a thought arises in you, ”What freedom! What happiness!” – soon you will become a dog. Whatever desire you keep within you, it becomes a seed. ”

Osho

From : Bliss: Living beyond happiness and misery