A multi-pronged brain fitness program includes nutrition, exercise, stress reduction, social interaction, sleep and stimulating activities. Cognitive fitness is the bedrock of a rewarding and self-sufficient life. The brain is constantly at work, even while you’re asleep. The brain communicates with systems throughout the body via neurons, or nerve cells, impacting your entire body. Reading books, playing word games and learning to play an instrument are all stimulating activities to impact cognition. Water is necessary in nearly every function in the human body, making adequate hydration crucial for maintaining good health. Research shows being dehydrated may impair brain function and cause low energy levels.