Franklin D. Roosevelt works out with Woodrow Wilson's cabinet

Walter Camp is known today as the "Father of American Football" for his contributions to the rules of the game, including the development of the line of scrimmage and the system of downs.

He was also an outspoken advocate of exercise and physical fitness.

With the entry of the United States into World War I in 1917, Camp was appointed director of the U.S. Navy Training Camps' Physical Development Program.

Disappointed by the sorry shape of most recruits, Camp devised a simple eight-minute exercise routine he called the "Daily Dozen," a sequence of calisthenic motions including "hands, grind, crawl, wave, hips, grate, curl, weave, head, grasp, crouch and wing."

The exercises were not meant to be particularly strenuous, and could be completed by young cadets and senior government officials alike.

In August 1917, Camp assembled members of President Wilson's cabinet and other officials to get them in shape for the war.

Among them was 35-year-old Assistant Secretary of the Navy Franklin D. Roosevelt, who would be paralyzed by polio four years later.

Check out the photos below: