Real Dictionary

effort
If you make an effort to do something, you try very hard to do it.
If you say that someone did something with effort or with an effort, you mean it was difficult for them to do.

effort in American English
the using of energy to get something done; exertion of strength or mental power
noun: exertion of physical or mental power

effort in British English
noun: physical or mental exertion, usually considerable when unqualified