Most of us were taught that human brains developed throughout childhood and then remained relatively unchanged for the rest of life. Now it is understood that our brains are changing themselves throughout our lives due to neuroplasticity.
Thoughts occur to us non-stop throughout the day. Some thoughts are positive, creative, and helpful, but other thoughts are negative and don't serve us
well. Perhaps a thought originated years ago when we needed it to keep us safe in a dangerous environment. Even though we are no longer in that environment, the thought remains as a pattern or habit.
Some people call unhelpful thoughts "negative self-talk" or ANTs (Automatic Negative Thoughts) -- thoughts such as, "I'm no good at this" or "Nobody likes me." They start out as thoughts but they become
so familiar that we accept them as facts.
Recognizing an ANT when it pops up and deciding not to think it any more is one way to stop practicing that thought, but that by itself probably won't work. It would be like trying not to think of a pink elephant.
But if we are aware that we are thinking an ANT and then replace it with a positive thought ("I am not good at
this yet, but I'm getting better and better," or "Many people are my friends and like me,") that will be much more likely to be effective. We’d be replacing a negative thought with a positive one, and at the same time we'd be laying down a new neural pathway in that more helpful direction!