Overthinking ushers in a host of adverse consequences:
It sustains or worsens sadness, fosters negatively biased thinking, impairs a person’s ability to solve problems, saps motivation, and interferes with concentration and initiative. Moreover, although people have a strong sense that they are gaining insight into themselves and their problems during their ruminations, this is rarely the case. What they do gain is a distorted, pessimistic perspective on their lives.
The How of Happiness