Thinking is a normal process and can not practically stop completely. One way to get better control on your thinking is via meditation.
It’s not the thinking which is the the culprit, it’s the content of the thinking. Usually negative thinking upsets us, as does non stop chain of negative thoughts.
Try to identify which recurrent repetitive thoughts are troubling you.
Next Steps
Seek consult from a good psychotherapist or psychiatrist to explore these thoughts and themes better
Health Tips
Learn meditation to take charge of your thoughts