Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), known by his pen name Mark Twain, was an American writer, humorist, entrepreneur, publisher, and lecturer. He was lauded as the "greatest humorist this country has produced", and William Faulkner called him "the father of American literature". His novels include The Adventures of Tom Sawyer (1876) and its sequel, the Adventures of Huckleberry Finn (1884), the latter often called "The Great American Novel".
You may find more from Mark Twain on Wikiquote
This is the true joy in life, the being used for a purpose recognized by yourself as a mighty one; the being thoroughly worn out before you are thrown on the scrap heap; the being a force of Nature instead of a feverish selfish little clod of ailments and grievances complaining that the world will not devote itself to making you happy.