You are the work.

Farmers direct the stream;

archers straighten the arrow's shaft;

carpenters shape the wood; 

the spiritual work on themselves.

Buddha

from the Dhammapada 10:17

The farmer knows his fields, the condition of his crops and how the seasons affect his harvest. He knows when water is plentiful and when it needs to be used judiciously. The farmer understands his medium. 

The archer knows her bow and arrow. She knows when the arrow is true and when it is must be straightened. Her craft is mastered by knowing the subtle nuances and conditions of her medium so that she can reliably hit her mark. 

The carpenter knows wood. He knows how it will split, which wood is soft and which is hard. He knows how the grain will appear and how to use the inherent qualities of the wood to produce a work of art. 

To practice the dharma we need to understand our medium. We are the medium, our own body, speech and mind. We are the wood to be shaped and the arrow to be straightened. We must understand the human condition in order for our practice to take root. Mastering our practice means understanding the human condition, and that starts by understanding dukkha.