English Translation
The spirit is willing, but the flesh is weak.
The TTS audio pronounces incorrectly. The transcription is correct. It should be こころあつけれど, not しんねつけれど.
This phrase is from Matthew:26-41 from the Bible. I found several translations in Japanese.
心は燃えても、肉体は弱い。(こころはもえても) (source 3)
霊はその気でも、肉体は弱いのだ。(れいはそのきでも) (source 4)
The original translation from Tatoeba doesn’t sound like a phrase from the Bible. The tone is not right at all. It sounds more like a proverb.