How Can the Prince Inherit the Throne If He Doesn't Maintain His Health?

Traveled through the Tang Dynasty and became the prince of the Tang Dynasty. But now that Emperor Xuanzong has been on the throne for twenty years and ushered in the prosperous Kaiyuan era, he is in the prime of life. Li Ying has just turned thirty, but is already frail and sick. Li Ying was afraid that she would walk in front of the emperor. So Li Ying started her own health-preserving life, setting a small goal first, to survive the old emperor to death!