Faced with such a complex situation, he was willing but powerless.
Tips
history
From the Southern Dynasties text 《高僧传》 by Huijiao (Liang dynasty): 贫道必当尽诚上答,正恐有心无力耳. A monk fears he cannot repay a kindness because, though willing, he lacks the strength.
usage
Often used to politely decline or apologize. Compare 力不从心 (near-synonym, slightly more about mental/physical incapacity) and 爱莫能助 (wanting to help but unable to).