As human beings, we evolved to avoid things that will kill us. “Is that a sabertooth tiger?! RUN!!!”
This focus on potentially negative things bleeds over from the physical realm into our mental realm. We’re constantly focused on the negative.
“So and so snubbed me.” “That person cut me off!” “Why do I always screw up?!”
We have a predominately negative slant to our thoughts. This burns through the energy you have to build the life you do want! If you’re always focusing on what you don’t want, how are you going to get what you do want?