There is no greater happiness for human beings than chanting Namumyōhōrengekyō.  The
sutra says, "The people there [in my land] are happy and at ease."  "Happy and at ease" here
means the joy derived from the Law.  You are obviously included among the "people," and
"there" indicates the entire world, which includes Japan.  "Happy and at ease" means to know
that our lives—both our bodies and minds, ourselves and our surroundings—are the entities of
ichinen sanzen and the Buddha of absolute freedom.  There is no greater happiness than
having faith in the Lotus Sutra.  It promises us "peace and security in this life and good
circumstances in the next." Never let life's hardships disturb you.  After all, no one can avoid
problems, not even saints or sages.
    Just chant Namumyōhōrengekyō, and when you drink
saki, stay at home with your wife.  
Suffer what there is to suffer, enjoy what there is to enjoy.  Regard both suffering and joy as
facts of life and continue chanting Namumyōhōrengekyō, no matter what happens.  Then you
will experience boundless joy from the Law.  Strengthen your faith more than ever.
                                                                    With my deep respect,
The twenty-seventh day of the sixth month in the second year of Kenji (1276)

The Major Writings of Nichiren Daishonin, Volume 1, p 161.