If you want a challenge, try this at home or anywhere. Learn to spin a book on your finger. This will make you enjoy more of your vacant time. It also helps your balancing skill developed. 1. Get a book. 2. Get your finger to the center of the gravity of the book. 3. Spin the book on your finger. 4. As the book spins, your finger gets outside of the center. 5. Try to get your finger back to the center and you can do that by moving your hand in a linear circular manner. 6. Keep practicing by spinning little by little until you can make it spin faster and faster.