In the Biographies of Promoters of the Lotus Sutra (Hung-tsan fa-hua chuan), there is the story about the monk Shih Fa-ch’eng (562–640), who was committed to the constant chanting of the Lotus Sutra as his vocation.
At one time, however, he was exhausted both physically and mentally and felt that he had to give up his practice. So he carried out a ritual program of worshiping Kuan-yin and prayed for protection.
When he finished the twenty-one day rite, he suddenly saw a giant in white standing in front of the Buddha image. The giant gave him some medicine and asked him to swallow it.
After that he became doubly vigorous in body and mind. He could then recite the sutra without stopping (T 8:37b).