Effort, exertion, pains, trouble mean the active use or expenditure of physical or mental power in producing or attempting to produce a desired result.
Effort may suggest either a single action or continued activity, but it usually implies consciousness that one is making an attempt or sometimes, even, is laboring or straining to achieve an end.
Exertion in general stresses the active, often vigorous, exercise of a power or faculty. Often, however, especially when not followed by of, exertion means a laborious effort.
Pains implies toilsome or solicitous effort; trouble implies exertion that inconveniences or wastes time and patience.