be diligent
勗 centers on persistent, careful effort: being diligent, working steadily, and applying oneself with sustained attention.
勗 is a rare character. It appears to combine 曰 (say, speak) with 助 (help, assist), possibly suggesting encouragement through words, but the exact historical development is uncertain.
The top 曰 looks like a mouth speaking, and the bottom 助 means help. Picture someone constantly speaking words of encouragement to help another person stay diligent and keep working.
For キョク, imagine a diligent worker who never stops, like a clock that goes 'kyoku, kyoku' with every tick, urging you to keep going.