Strategy # 1: Interrupt the Pattern. Thoughts, can turn into physical responses, in your body. Stress, depression or frustration, can lead to physical responses in the body. SO interrupt the pattern, get away from the thoughts. Walk, Work out, or mediate. It will change body chemistry. Which in turn can affect your thoughts. A good run, often changes attitudes.
Strategy # 2: Positive Replacement. For every negative thought, you think, you must come up with 2 positive perceptions. This will condition your mind to look for the positive in each situation. Soon, you start looking of the good in every situation FIRST.
Eventually eliminating the negative. I just said to my daughter Meg. Every day above ground is a GREAT day. I only have GREAT, GOOD and OK days. All the rest Suck so why think about them.
All events, can have a positive side, if you look for them. My Mum died of lung cancer. It was a terrible death. I miss her a lot. I decide to think about the positive. Her pain is over. She is in a better place. She gave me so many years of growth, character building and life skills.
Strategy # 3: Look back from the Future. Put yourself 20, 30, 40 years in the future. Will that problem be a big issue? Will it Matter? Will it look small compared to the rest of your life.
Strategy # 4: Look for laughter. Go to comedy club. See a movie. Read Jokes or listen to funny monolog. Hard to think negative when you are belly laughing. Laughter is good for the soul and health.
Strategy # 5. Find a Distraction. Go fix that car problem. Help someone else with their problems. Clean the house. Take friend for a drink (1 not many).
Some ideas to kill those negative thoughts.