They are the men and women who have the courage to strive for the happiness which comes only with labor and effort and self-sacrifice, and only to those whose joy in life springs in part from power of work and sense of duty.
 Theodore Roosevelt, Theodore Roosevelt; an Autobiography (1913). copy citation

Context

“But there is no other success that in any shape or way approaches that which is open to most of the many, many men and women who have the right ideals. These are the men and the women who see that it is the intimate and homely things that count most. They are the men and women who have the courage to strive for the happiness which comes only with labor and effort and self-sacrifice, and only to those whose joy in life springs in part from power of work and sense of duty. CHAPTER X THE PRESIDENCY; MAKING AN OLD PARTY PROGRESSIVE
On September 6, 1901, President McKinley was shot by an Anarchist in the city of Buffalo. I went to Buffalo at once. The President's condition seemed to be improving, and after a day or two we were told that he was practically out of danger.” source