run out of steam

US /rʌn aʊt əv stiːm/
UK /rʌn aʊt əv stiːm/
"run out of steam" picture
1.

勢いを失う, 疲れ果てる, 気力がなくなる

to lose energy or enthusiasm and stop doing something, or to become tired and less effective

:
The project started strong, but it seems to be running out of steam now.
プロジェクトは好調に始まったが、今は勢いを失っているようだ。
After working for ten hours, I started to run out of steam.
10時間働いた後、私は疲れ果てた