These old habits are dangerous only, because we are no longer conscious of how our mood changes. The alterations are that subtle. It’s like eating or breathing; it just happens without our consciousness being aware of it. Repetition will intensify the patterns and, just like any addiction, even if we are aware of them - become harder to break and correct.
How do we break such a strong habit? Just as we repeated these habits over and over again over the years, so must we repeat our new mind model over and over again until our sub-conscious goes to the new thought automatically. It takes patience, but we can accomplish this new and improved mind-set little by little.
Try it and you will see a change in your experience, your relationships and your happiness. Wishing you all the goodness in the world!