One of the first big civ's in SEA ( I forgot if it was the harrapans or in (one of?) the first megacity, near present day angkor wat), The king had to climb a pretty steep climb after every day of work, so if they got really old or glutonous, he couldnt use the kings house and thus not be king anymore. Obv the idea is flawed, but I kind of like the idea of a built in physical test, that would disqualify you from a position of serious power if you fail to pass it.