Let me start off simply by saying that I have been there a lot and so have many other people. In fact, you probably wake up with dozens of things on your mind and no way to work through them. It can be a scary world inside your head some days.
The most important thing to know is that you are not alone.
I can honestly say that there are going to be times that it is hard and you're not going to want to and in fact, you might even resist it. No matter, though, what you need to just let it go and allow things to be what they will. For you, overthinking probably takes many different forms (and its not always obvious to those around you). It could be something that is running through your head that criticizes and picks apart what you said and did yesterday that makes you afraid that you caused someone trouble or did something that might make them think less of you.
You probably feel like you are constantly being judged by the world around you and are often afraid to say things because of that fear. I've definitely felt that way before. You are not alone.
Overthinking can easily take control of your life.
I mean it. It takes one thing and suddenly you feel like you're not in control anymore. it can put your mind in a state of constant worry and you feel like there's not much, if anything at all, that you can do about it. You might even start thinking "why do I feel this way, it's stupid." It's not. I promise.
I'm not here to tell you to stop, because I know how hard that can sometimes be, but I am going to tell you that sometimes talking about it with another person is one of the best things that you can possibly do.
The good news for you is that this is not a permanent state of mind.
So the next time you catch yourself in your head, try one of these things. Talk yourself out of it. This may be one of the hardest things to actually do, but once you do, it can be so freeing. Instead of just telling yourself to not have that negative thought, try replacing it with a different one. If that doesn't work, try keeping a journal or writing down what you are feeling every time you feel it. For me, this is something that has helped a lot.
Finally, ask yourself what exactly it is that you are overthinking about. Is it something about your future? Something you can't control? Because if you can't control it, putting all of your mental energy into it isn't worth it.
So, the next time you catch yourself overthinking remember these things and maybe, just maybe, you'll start to feel some of that pressure come off and lift your mood.