In a book a read a while back it explained why we should focus on what we do want instead of what we don’t want.
It gave the example of someone telling you not to think of a purple elephant and how despite being told not to that is exactly where the mind wanders. That simple example is the same for our wants and goals. It’s the reason why the focus should be on the things that we actually wan’t.
When you spend time focusing on what you don’t wan’t your mind will give energy to those things. Your mind will visualise and think about these things which will only amplify them in your physical reality.