Reading and pondering the scriptures will bring much strength and comfort to your life. Blessings, Gar
Dr. Scripture says this about negative thoughts
Have you ever been offended, become frustrated or impatient with something or someone? Have you ever been cut-off at an intersection while making a left hand turn and almost had an accident?  Have you ever surprisingly seen something, i.e. on TV or on the internet that you wished you hadn’t and then had a hard time getting it out of your mind? Relief requires a special treatment of scripture-boosting.
Almost everyone has a favorite sacred verse. Do you have a favorite scripture that you know by heart and can recall at any moment? My scripture is taken from the Book of Mormon and repeating it when I have felt any of the above has been helpful to rid myself of many negative thoughts immediately.
1 Nephi 3:7
And it came to pass that I, Nephi, said unto my father:
“I will go and do the things which the Lord hath commanded, for I know that the Lord giveth no commandments unto the children of men, save he shall prepare a way for them that they may accomplish the thing which he commandeth them.”
I recommend that this scripture be repeated as needed.
Taking a few seconds to mentally repeat this scripture in your mind will give you the leverage needed to get past a negative thought that has gotten into you head.  The longer a negative thought is allowed to stay in the mind, however, the more difficult it becomes to get it out. But, it is not impossible to get rid of it.
I started practicing this technique immediately after I heard a great teacher say that he needs to read the scriptures to get rid of a negative thought or experience. “Aha!", I thought, "I can do that as well!” I was surprised to learn that immediately after repeating the above scripture that a negative thought went away and didn’t come back for a long time. Of course, if I thought about that negative experience again the thought did come back. Then, I had to repeat the scripture-boosting process which helped get rid of it. Yes, I have learned that not only will the scriptures give us a better understanding of the purpose of life, but repeating and pondering them will enable us to feel the power and strength of God in our lives.