1. Relax your head, grab the feet of the yoga mat with both hands, and pull up the fitness mat when you tuck in. Yoga mats can be replaced by towels, with the waist always attached to the ground and the hips slightly raised.
2. Inhale when lying on your back.
3. Exhale when rolling your abdomen. Reasonable breathing is the key factor to ensure lasting exercise.
PS: During the whole process, the neck is in a relaxed state, and the abdomen contracts when rolled up, especially in the upper abdomen.