Thoughts do not intrinsically have any power AND they are the beginning of all creation, they are part of the creation process, and they begin to create our reality. So, if they have no power, where does the power come from? The power comes from you! The power comes from your engagement and/or participation with them. The power comes from the intensity of the current thought and the intensity of past similar thoughts. The power comes from the repetition of the thought (how often you think about the thought). Last but not least, the power comes from how much you believe in the thought as you are thinking it.
Most people believe their thoughts are real. They engage, they participate, and they give power to the thoughts. They often do not mean to do so; it happens because of habit and lack of self awareness.
For this reason, I ask people to begin to observe their thoughts, watch their thoughts, and then pick and choose the thoughts with which they would like to participate. To do this, the practice of observing thoughts must come first. You have to be able to observe any thought, no matter what the thought is, and begin to practice non-resistance, complete acceptance and see them for what they are, leaving them well enough alone. Once you practice that for awhile, you will then be able to pick and choose, and then participate with those thoughts from a place of Consciousness, Awareness and purpose.