The brain does not distinguish between imagination and reality
Our "intelligent organ" brain, perceives even the things we imagine as real. The brain never rests, for example, if a girl doesn't wait half an hour for her boyfriend to come back, thoughts like "he's dumped me", "he's cheating on me", "he's not interested in me" etc. is accepted as an orientation. Although the brain is able to avoid uncertainty and reduce anxiety, it does not stop working. The girl's thoughts are floating in the middle of speculations, "is he leaving me?", "maybe he has another woman", "let's get everything ready", "let's change the locks", "what will mom and dad say?" "Yes", "I'll show you who you broke up with", "I'll make you feel good about who you broke up with" and so on. Mixed with his thoughts, he loads his brain with these thoughts, which combine love and hate. However, how much did the girl complain about the fact that her boyfriend was in an important meeting, locked his phone in the car and couldn't pick it up, or came late due to incidents? In any case, it is necessary to imagine things well.
The brain can be changed
The more new information is received, the more neural connections are formed in the brain. The information we stream is stored at some level as images and memories. But systematically filling up the "database" allows for more pictures and memories. That's why scientists have a faster thinking speed and a very good memory. Their brain's gray matter, which is normally thought-provoking, is regenerating in a coordinated fashion, allowing the brain to function at a very high level of efficiency. Therefore, you should try to study anything systematically.
The brain works independently of us
Most of the time, the brain processes the information it has, regardless of our will or free will. When we are at work or when we talk, we can't control our brains for a while, but we can't control our brains at other times. When the situation changes or new information is not introduced, the brain works with old materials. For example, if you spent yesterday thinking about unpleasant things, it means that you will have the opportunity to do so today. So, try to fill your “database” with relevant information to control your thoughts and guide you in the direction you need. Always try to think of good and pleasant things.