all pain and no gain; lots of effort, little reward
Proverb-like expression meaning that despite great effort, the results are meager. Often used to lament an inefficient or thankless task.
This job is all pain and no gain.
It was a project with lots of effort and little reward.
Similar meaning: 'all that effort for nothing'. More colloquial and vivid, literally 'losing the effort and gaining only fatigue'.
A classical Chinese-derived expression (労多くして功少なし) that entered Japanese as a set phrase. The exact historical origin is uncertain, but it follows a common pattern of contrasting effort (労) and result (功).