In the beginning, you want to develop sensitivity to the bottoms of your feet, or the “Bubbling Spring,” also called “Bubbling Well,” or in Chinese, Yongquan. As you practice over time and develop your gongfu, that feeling that you once had to concentrate so much in order to develop now results from a more-mature practice.
Gongfu = Effort done over time that creates knowledge and ability.
A highly sensitized bubbling well liberates you from the initial task of focusing attention on that spot and sustaining concentration as you move from, or through, it mindfully.
Once that’s achieved, you can move on and focus on other aspects of practice, such as other parts of the body and the physical mechanics of movement, or the energetic configurations of your movement.