And yok'd each eve a grinder's task to fill.
At last it groan'd and said, "What courses past,
Round what strange millers' turns I wheel at last!"
Be not too much with fortune's hopes elate;
Age ends for many in a troubled state.
Source: Davies: Fables of Babrius = Babrius 29.
(image source: although this is a donkey, you get the idea)