A hardworking person; someone who steadily puts in effort and perseveres in work or study.
彼女は本当に努力家で、毎日遅くまで練習している。
She is truly a hard worker and practices late every day.
才能だけでなく、努力家であることも成功の要因だ。
Not only talent, being a hard worker is also a factor in success.
あのチームには努力家が多く、練習量が勝因になった。
That team had many hardworking people, and their amount of practice became the reason they won.