at it

I'm too voluminous—I'm a boiler-over, not a simmering stick-at-it.

They will not, however, have the more methodical stick-at-it quality of those whose fingers are found firm and stiff.

He likes to talk of empires and dynasties falling, and thousands of years gone by, and Good-God-look-at-it-all-now sort of thing.

There's so many fact'ries nowadays that Keep-at-it is the only sewin'-woman that makes a livin'.