In On Prolonging Life and In Dealing With Disaster, Nichiren teaches (listen carefully)

"Answer: The forces of karma do not operate in fixed ways. There is what is called karma that manifests itself in one’s present existence. Describing such cases, the Lotus Sutra says that a person “will in his present existence be afflicted with white leprosy.... And he will suffer from... severe and malignant illnesses.”25 The Benevolent Kings Sutra states: “If persons destroy the teachings of the Buddha, they will have no filial sons, no harmony with their six kinds of relatives, and no aid from the heavenly deities. Disease and evil demons will come day after day to torment them, disasters will descend on them incessantly, and misfortunes will dog them wherever they go.” And the Nirvana Sutra states: “If there are those who fail to put faith in this sutra, when they approach the time of death, they will encounter a world troubled by disorder, armed strife will break out, or they will find themselves the victims of the tyranny of rulers or the quarrels and contentions of warring families.”

Regarding the second type of karma, that which manifests itself in one’s next existence, the Lotus Sutra says, “If a person fails to have faith but instead slanders this sutra, . . . When his life comes to an end he will enter the Avīchi hell.” And the Benevolent Kings Sutra states: “If persons destroy the teachings of the Buddha, . . . when they die, they will fall into the realms of hell, hungry spirits, and animals.”" - In Dealing With Disaster

"Life is the most precious of all treasures. Even one extra day of life is worth more than ten million ryō of gold. The Lotus Sutra surpasses all the other sacred teachings of the Buddha’s lifetime because of the “Life Span” chapter. The greatest prince in the land of Jambudvīpa would be of less consequence than a blade of grass if he died in childhood. If he died young, even a person whose wisdom shone as brilliantly as the sun would be less than a living dog. So you must hasten to accumulate the treasure of faith and quickly conquer your illness.

If you are unwilling to make efforts to heal yourself, it will be very difficult to cure your illness. One day of life is more valuable than all the treasures of the major world system, so first you must muster sincere faith. This is the meaning of the passage in the seventh volume of the Lotus Sutra that states that burning a finger as an offering to the Buddha and the Lotus Sutra is better than donating all the treasures of the major world system. A single life is worth more than the major world system. You still have many years ahead of you, and moreover you have encountered the Lotus Sutra. If you live even one day longer, you can accumulate that much more benefit. How truly precious your life is!