keep one`s nose to the grindstone

Verb
1. work doggedly or persistently; "She keeps plugging away at her dissertation"
(synonym) plug away, peg away, slog, keep one's shoulder to the wheel
(hypernym) work

work hard or keep busy for a long time He has been keeping his nose to the grindstone all year so that he can save up enough money for a new car.

idm. ทำงานหนักและต่อเนื่อง (คำไม่เป็นทางการ) (syn. get back to)