Sri Sri Muralidhara Swamiji
An ordinary man (not a sădhak) thinks that he has only one thought at a time. But, it is not so. Innumerable thoughts keep rising up in him and they compete with each other to take hold. A particular thought takes hold and the person thinks that he has only this single thought in him. But, when we sit to do japa or ătma vichăra we find that countless thoughts keep raising one after another, in a gush. Through japa, we control all thoughts and try to concentrate on a single thought.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji