What a wonderful topic to start the conversation about. I agree with you on this totally. Overthinking is just a weakness Which develops when you are not contented. Nowadays overthinking is often misconstrued as rational thinking or logical thinking but the irony is the more you think, the more you are stressed.
In addition, many psychiatric diseases are associated with overthinking. It needs to be stopped as soon as possible. What I have personally tried and succeeded doing is reflecting upon my thoughts. Every hour or two, I pen down the type of thoughts I had and at night I review them. This has really helped me in changing my thinking pattern and has enabled me to think correctly according to the situation. Rajyoga meditation (connecting to the real self) has empowered me to stop my overthinking and gain control over my mind.
I would again like to congratulate you on writing a wonderful piece of life lesson. Great work.