Cats are extremely insecure animals. Curling up into a ball can relieve the cat's mood. Most of the time, cats curl up into a ball to reduce the dissipation of body heat. When the indoor temperature is low, you can prepare to be comfortable. Give the cat a soft pad to prevent the cat from catching a cold. Sometimes the cat will do this when it is bored. The owner should spend more time with the cat, care about it, and play with the cat.