With your talents and industry, with science, and that stedfast honesty which eternally pursues right, regardless of consequences, you may promise yourself every thing—but health, without which there is no happiness. An attention to health then should take place of every other object. The time necessary to secure this by active exercises, should be devoted to it in preference to every other pursuit.
Thomas Jefferson, letter to Thomas Mann Randolph, Jr. (July 6, 1787); in Julian P. Boyd, ed., The Papers of Thomas Jefferson (1955), vol. 11, p. 558.