He worked without sparing any effort.
Years of toil bore fruit.
He devoted all his efforts to rebuilding the company.
I would like to thank everyone for their efforts.
努力 is the everyday word for making an effort toward a personal goal, while 労 is more formal and carries a stronger sense of toil or trouble.
労 (effort, toil) and 老 (old age) share the same reading ろう but are unrelated in meaning, so listeners must rely on context or kanji.
labor; labour; work · Labour Party
trouble; hardship; difficulty; labor; toil; pains · anxiety; worry; concern; cares
fatigue; weariness; exhaustion · metal fatigue
labor; effort; toil
trouble; hard work · thank you for your hard work; I appreciate your efforts
overwork; excessive work; strain from overwork
working; being employed; employment
work-related injury, illness, or death; on-the-job accident · workers' compensation insurance
labor union; trade union
The kanji 労 is composed of 力 (strength) and a simplified form of 熒 (to shine), suggesting exertion that consumes energy. The reading ろう is the on'yomi.
labor; work; diligent service
labor; work; service
labor and management
meritorious deed; distinguished service
mental strain; anxiety; worry
worldly-wise person; person who has seen much of life
labor union; trade union
fruitless effort; wasted effort; futility
recognition of services; appreciation for hard work
labor; toil; hardship
fishing; fishery
physical labor; hard manual work; toil
toil; labor; laborious task · painstaking work; work of great effort
labor administration; labour administration
trouble of going somewhere; inconvenience of making a trip
unearned; without labor
tired out; exhausted; weary
meritorious deed; distinguished service
pulmonary tuberculosis
labor-relations board
tabes; phthisis; pulmonary tuberculosis