Here's what intrusive thoughts are and how to alleviate them.

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CNN  — 

Have you ever been hiking with your partner when you suddenly imagine pushing them off a cliff? Or on your way home from work, you can’t shake the feeling that you hit someone with your car without realizing it? What about loving your colleague’s cologne and fretting it must mean you don’t love your husband? 

These are intrusive thoughts, which are “repetitive and unwanted thoughts that can seemingly come out of nowhere,” said Dr. Sue Varma, a New York state-based psychiatrist and author of the upcoming book “Practical Optimism: The Art, Science, and Practice of Exceptional Well-Being.”