In any given day, the number of things you can think about is finite.
You have to make choices about what you allow to occupy your mind.
I had the epiphany a month or so ago that I was giving up a huge percentage of the space of my brain to thinking about things that were not truly what I wanted to be focused on. It occurred to me that if I removed those things from my life, I would open up a tremendous amount of real estate in mind. I would be able to spend time thinking about things that truly excited me and that produced a much better return on investment.
Your brain is valuable real estate.
What are you choosing to fill it up with?