1. British statesman, Edward Stanley the 15th Earl of Derby, made this statement in ones of his speeches in 1873.
2. Sallis RE. Exercise is medicine and physicians need to prescribe it! Br J Sports Med. 2009;43:3–4.
3. Casperson CJ, Powell KE, Christenson GM. Physical activity, exercise, and physical fitness: definitions and distinctions for health related research. Public Health Rep. 1985;100:126–31.
4. Ricketson S. Means of preserving health: founded principally on an attention to air and climate, drink, food, sleep, exercise. New York: Collins, Perkins; 1806. p. 152.
5. Warren JC. Physical education and the preservation of health. Boston: William D. Ticknor; 1846. p. 90.