Can we think without words, what thoughts do infants have before they learn to use words. We feel an intense responsibility for the thoughts we have, and we feel an obligation to think them through to the bitter end. We are not to blame for the thoughts we have, but we are responsible for what we do with them , once they appear in our conscious mind. Just because a thought pops into our mind, we don't have to spend time on it, we are not obligated to think about it. Don't fight with the thought or worry, just LET IT GO, by not spending time on it, or judging it.
Thoughts can come from almost anywhere, the conscious or the unconscious mind.
Consciously we may be exposed to an external stimulus, in a conversation with someone, reading, TV, or consciously reviewing things in our mind. An example I often use in my stress management program, is a personal experience from my work as a paramedic. I describe driving in my car with my wife and 3 year old daughter, when suddenly we pass a certain intersection that I haven't been by in about 10 years. A thought suddenly appears in my mind of the last time I was at that intersection. I had responded to a motor vehicle accident there, involving a young mother as the driver and her two 3 and 4 year old boys.