Using near-infrared technology, the device can reflect real-time brain activity levels to indicate effective brain training methods for the individual brain. Coupled with brain training games, real-time feedbacks are analyzed to adjust difficulty levels of games to enhance brain activity levels. Thereby, improving the quality of life, work, and learning, as well as preventing cognitive impairment. Stress Manager is a new associated app of ExBrain XB-01 Brain sensor. It has two major functions: 1. Breathing Meditation and 2. Biofeedback Training. In short, the app provides guided meditation and brain training exercises. By measuring DMN, the active part of the brain in an idling state, the brain sensor tracks users’ heart rate and brain activity, and lets users relieve their stress and learn to control their mind/brain activity.