Sisyphean fight/ task

In the generation since, millions have given up smoking, though 400,000 still die from the habit every year. But colleagues said Dr. Davis stayed in the Sisyphean fight against smoking and other health hazards in a nation of fast foods, caloric binges, lazy ways and the anodynes of liquor and cocaine

Sisyphean

(sĭs'ə-fē'ən)

adj.

1. Greek Mythology. Of or relating to Sisyphus.
2. Endlessly laborious or futile: “Their patients' lack of education and the high cost of medicine make health care a Sisyphean task” (Frank Gibney, Jr.).

[From Latin Sisyphēius, from Greek Sisupheios, from Sisuphos, Sisyphus.]

Sis·y·phus (sĭs'ə-fəs)
n. Greek Mythology.

A cruel king of Corinth condemned forever to roll a huge stone up a hill in Hades only to have it roll down again on nearing the top.

[Latin Sisyphus, from Greek Sisuphos.]