Reading. Song Meiling especially liked reading Neijing when he was young. In Huangdi Neijing, Su Wen wrote that moderate diet is one of the keys to longevity, and improper diet will lead to premature aging. Food restriction can not only reduce the gastrointestinal burden, but also stimulate the autonomic nervous system, endocrine system and immune system in a semi-starvation state, thus mobilizing the self-regulation function of the human body, promoting the balance and stability of the internal environment and enhancing immunity. Often full will make people old and damage their health.