When we have the same thought again, the line of the original thought is deepened, causing what's called a memory trace. With each repetition the trace goes deeper and deeper, forming and embedding a pattern of thought. When an emotion is tied to this thought pattern, the memory trace grows exponentially stronger.

Unglued: Making Wise Choices in the Midst of Raw Emotions (ed. Zondervan, 2012) - ISBN: 9780310332800