diligent; hardworking; conscientious
Describes a person who works steadily and reliably, often with a sense of earnestness and attention to detail. Common in everyday speech.
He diligently keeps a diary.
A hardworking person is trusted.
Dated usage for being in good physical condition. In modern Japanese, 元気 or 健康 is more common.
Thankfully, I am in good health. (archaic phrasing)
Dated usage for being loyal or sincere. Today, 忠実 (ちゅうじつ) or 誠実 is normally used for this meaning.
He served his lord faithfully. (archaic phrasing)
He diligently writes letters on a regular basis.
She has a diligent personality and always keeps her room tidy.
I clean up diligently on a regular basis.