According to Osho, just watching means witnessing whatever arises in the mind without interference, but he warns it can take years and remain uncertain because you keep creating new mind atop a vast past accumulation. It works mainly if your inner “madness” is small; otherwise the watching feels endless, so assess your condition before depending solely on this method.
Look at your thoughts come and go, but know it may take a very long time unless your mind is already quiet.