One of the things I've found amazing lately is a ball that is used for exercise. It's about 70 to 80 centimeters in diameter, filled with air, and made of scientific resin. By just sitting on it and jumping around, you can strengthen your abdominal muscles and remove strain on your spine and pelvis. I couldn't understand the principle behind something that moves so simply. I am a skeptic, but when I saw professional athletes using it, I was convinced that it was true. It also makes my internal organs stronger.