Jayapataka Swami: Then He will allow you to do so. If you want to think of Him, He will allow you to do so. You should decide to only think of Krsna. Now the guru of Ramanujacarya, Yamunacarya, had said that when he chanted japa, if he thought of sex life, he would spit on the thought, cha! because he had developed a higher taste. But even such a great devotee sometimes, this thought came in his mind! How would you yuck! What do you think of that? So you asked the question, how do bad thoughts come to our mind and how do you react to it? If you are told, I like to eat some non-mentionable things, oh, yuk, it is horrible. We should take out all the evil thoughts from our mind and pray to Krsna to put good thoughts in our mind.