godan verb (-mu), intransitive verb
work hard; strive; devote oneself
Intransitive verb for putting sustained effort into something, often with a goal or duty in mind. Commonly used with に or ことに to mark the target of effort.
彼は毎日、試験勉強に励んでいる。
He works hard at studying for the exam every day.
健康のために、運動に励もうと思います。
I intend to devote myself to exercise for my health.