long haul

Từ điển Oxford Advanced Learner 8th

ˌlong ˈhaul 7 [long haul] BrE NAmE noun usually singular
a difficult task that takes a long time and a lot of effort to complete
•She knows that becoming world champion is going to be a long haul.
Idioms: ↑in something for the long haul ▪ ↑over the long haul