Born on this day to one of the wealthiest families in New York City, Theodore Roosevelt (1858–1919), 26th U.S. President, remembered himself as a “sickly, delicate boy.” He took up vigorous exercise and found breath and courage. That steady determination shaped a life of great successes and enduring service.

He measured himself by inner standards. “I care not what others think of what I do, but I care very much about what I think of what I do. That is character!” he said. “Like all Americans I like things big—big prairies, big forests, big factories, and everything else.”

In 1898 he led the Rough Riders in the Spanish–American War, returned home a hero, and became Governor of New York. Two years later, he was elected Vice President, and in 1901, after the assassination of William McKinley, Roosevelt, 43, became the youngest President in history.

“Nine-tenths of wisdom is being wise in time,” he said—and lived by it.

With energy that refused to idle, he helped drive the Panama Canal, built up the Navy, and received the 1906 Nobel Prize for mediating peace in the Russo–Japanese War. He wrote more than thirty-five books and lived with passionate zeal. “I always believe in going hard at everything,” T.R. said—and he did, for the common good.

A devoted naturalist, he established the U.S. Forest Service and safeguarded 230 million acres of American land. Eighteen national monuments began under his pen—gifts set aside so future children could know wonder and call these places home.

His lesson is simple: begin where you are, and move forward with heart.

“Let us remember that, as much has been given us, much will be expected from us, and that true homage comes from the heart as well as from the lips, and shows itself in deeds.”