The Reborn Super Doctor

The doctor explains that he is using the "pureest wood attribute" of internal energy to speed up the regeneration of a patient's skin and hair. The patient in the next room is much worse than the one he just treated, but the doctor says that the patient is much better than he is. The doctor then explains that the number of cells in a person's body is proportional to the amount of time he spends on the task at hand. He says that, although the internal organs of the patient are in good shape, he is too old, and the cell divisions in his body have reached a "certain level"