Overthinking is a cause of great misery. We tend to complicate our life with numerous thoughts. Some of it can be constructive while most being painful. I read somewhere 22000 different thoughts crosses our brain every hour. In the case of sages, yogis it is much less.
Vipassana and other eastern meditation talks in great deals about our thoughts. If we can get over this overthinking, we will start living in the present. Once we start living in the present, we will see the world as it is.