As you live your life, aware of your environment and all of its contrasting components, a natural process of clarifying your personal preferences occurs. Sometimes these preferences are so fully conscious that you speak of them in terms of your desires, and sometimes they are more subtle and no words are spoken, for these preferences happen at many levels of your Being.
It makes no difference whether the thought you are thinking is one you have deliberately chosen to focus upon, or whether you are merely lazily observing something and therefore thinking the thought - you are still thinking the thought, offering the vibration, and reaping the manifestation results of that thought.
When you think of only of what you desire, without constant contradictions that are filled with doubt or disbelief, the Universal response to your desire comes quickly... But that kind of thought takes practice.