Lucius Annaeus Seneca: Your true happiness
True happiness is to enjoy the present, without anxious dependence upon the future, not to amuse ourselves with either hopes or fears but to rest satisfied with what we have, which is sufficient, for he that is so wants nothing. The greatest blessings of mankind are within us and within our reach. A wise man is content with his lot, whatever it may be, without wishing for what he has not.
Seneca the Younger (c. 4 BC – AD 65), fully Lucius Annaeus Seneca and also known simply as Seneca (/ˈsɛnɪkə/), was a Roman Stoic philosopher, statesman, dramatist, and—in one work—satirist of the Silver Age of Latin literature.