Our health, courage, wisdom, joy, desire to improve, self-discipline, and so on, could all be said to depend on our life force. Chanting Nam-myoho-renge-kyo enables us to bring forth limitless life force. Those who base themselves on chanting Nam-myoho-renge-kyo are therefore never deadlocked.

From The Wisdom for Creating Happiness and Peace, part 1, revised edition, p. 101