Although one thought isn’t going to make a difference in your mental well-being, ruminative, negative thinking has a cumulative, mind-body effect (depleting you both emotionally as well as chemically) eventually contributing to anxiety or depression.
You need to know that thoughts matter and there’s an emotional and physical price to pay for needless shabby thinking. Recognize that "shabby" negative thinking is a choice of passivity (i.e., you sit back and allow your habits of insecurity to go on and on unimpeded). Instead, start to become a more active thinker, especially when you're feeling stressed and challenged.
Choose to reject insecurity-driven thinking. Starting today, take responsibility--one thought at a time—STOP dancing with negativity.