Good day my Friend. I can understand your concern.
Overthinking is an outcome of worry or fear about past or future. May be worrying about some past bad memories or relationship or family matter .or May be having fear about some health issues or financial issues etc.
So it's important to understand your background, bothering issues, other physical and mental symptoms to recommend suitable solutions. General advices or suggestions will not be effective here.
Be positive. It's an addressable issue if are willing to make few changes in your mindset, lifestyle, food habbit, daily routines and follow certain therapies. Without making any changes you can't expect results. Are you willing to make these changes?.
If so feel free to reach me online for further assistance and assessment of your physical and mental symptoms to recommend suitable non medicine alternative solutions.
Health Tips
go through my videos on self therapies to handle.Anxiety..https://youtu.be/c22_uIJqtlI