From the ArcaMax Publishing, Vocabulary Newsletter:
http://www.arcamax.com/news/vocabulary/s-355795-281629
constitutional \kon-stih-TOO-shuhn-uhl; -TYOO-\ (noun) - A walk taken
for one's health.
"A wise physician does not simply give a tonic for a diseased limb, or
a high fever; the patient might be dead before the constitutional
remedy could become effective." -- Charles Waddell Chesnutt, 'The Wife
of His Youth and Other Stories'
A constitutional is so called because it is taken for the benefit of
one's constitution.