Definition of "work on" [work on]

• To shape, form or improve something (verb)
• To exercise influence on someone (verb)

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• "Meanwhile, unbeknown to her, her two-year-old is coming down with a coxsackievirus she picked up at daycare, and Mom just shared the end of a Popsicle with her, so the virus is beginning to work on her mast cells as well."
• "David and Chris Stewart, accompanied by the dog, take a seven-and-a-half- mile walk through the haunts of the Carter familyWe drive from Bristol to Cornwall in just a few hours, which reminds us that Cornwall has become close enough for city types to weekend in their cottages and get back in time for work on Monday – a far cry from the days the journey must of taken in Harry Carter's time."
• "Today, LaShekia, who has since graduated from college and begun work on a novel, has spent nearly a decade and a half battling a total of five different devastating autoimmune diseases, two of which—lupus and scleroderma—can bring normal existence to a halt, or even end a life."