Hyakujo - who was a famous Chinese Zen teacher would work alongside his students even when he reached the ripe old age of 80. His work included tending the gardens keeping the monastery grounds clean and tidy.
His students felt he should stop work and rest his aged body but he just would not listen to their advice. So to make him stop they hid away his tools where he couldn't find them.
The very next day Hyakujo refused to eat and he repeated this the day after. The students reflected on their actions and decided to put his tools back in the place where he had taken them.
That night the Zen master worked and ate as was his normal routine. When he had eaten he told his students “No work, no food”.