You are going with obsessional ruminations so take consultation

Dear Madam You are seeking help here means it's really creating a problem in day to day life. I am not sure how much tips and tricks would work because I have seen people that it is very difficult to practice it as mind automatically goes away now and then. I have suggested writing down these hindered of thoughts in dairy, do yoga and meditation but most of them find it difficult to practice as mind wondered away while doing these activities. What I found helpful is doing deep breathing exercises every time you realized you are overthinking. Second is spending more time in hobbies or engaging in a hobby you enjoy it. However, you should be clear that overthinking may be a part of anxiety such as apprehension, inability to concentrate, being anxious or fearful, expecting untowards may happened. If such is the situation than medication and psychological help may be needed for proper control.

Overthinking - one of the most common Yet most annoying issues . Overthinking isn’t bad if something good comes out of it. Observe what themes visit your mind often. Don’t fight the train of thought. Instead just notice it. Notice how your body reacts too. If you get a chance, write a bit about it as it is helpful in therapy.

Hi, I will suggest to journal everything which is going in your mind and bothering you. Notice your thoughts, feelings, any particular images and try to introspect from where they are coming, has something happened in past or are you worried about something for future, try to see things from different angles and think about the ways how you can react differently & deal with it. You need to invest sometime on yourself for this and still it bothers you then you can take professional help of any Psychotherapist.

Notice When You're Thinking Too Much. Awareness is the first step in putting an end to overthinking. ... Challenge Your Thoughts. ... Keep The Focus On Active Problem-Solving. ... Schedule Time For Reflection. ... Practice Mindfulness. ... Change The Channel.