Some say that the prenatal Jing is fixed, and once depleted, is unable to be restored, and that ageing is inevitable (think about all of the signs of ageing - brittle bones, hair loss, skin sagging, fatigue, menopause) these are all manifestations of weakening Jing.
Many would disagree, however, there are certain practices that you can undertake to explore your own potential in this space. These are some simple practices to consider when protecting/cultivating your own Jing Essence.