Overthinking is the act of continuously dwelling on the same thoughts, often leading to stress, anxiety, and emotional exhaustion. It affects mental health by increasing worry and negative emotions, which can impact sleep, concentration, and overall well-being. Physically, overthinking can lead to headaches, fatigue, and increased risk of heart-related problems. To control overthinking, it’s important to practice mindfulness, engage in physical activity, set boundaries on worries, and focus on solutions instead of problems.