What do you want to do sadhana for? The aim should not be the satisfaction of egoism: "I want to be a great yogi; I shall have so much power and with that power I shall establish myself in the world." All such thoughts must be thrown far away.
It's the same thing that drives people to want to experience sexual pleasure or have one too many drinks. We all want to experience the other, and to get out of our daily existence.