Ultimately, you have to have the heart to do it.

最终，你还必须全心全意去做这件事。

I don't have the heart to do that.

我不忍心那样做。

I didn't have the heart to do that.

吉尔：我不忍心那样做。

Now, if you have the heart to do it, lie low, keep still, and imitate the call of the hen quail.

假若有人有心，不妨蹲下，保持沉默，模仿母鹌鹑的叫声。

However, I have some concerns about this project." " We have the hearts to do this.

但是，我对这个项目有些顾虑。” “我们有心去做这个。

Didn't have the heart to tell Mr. E. He didn't have the heart to do it; it's just too mean.

不忍心告诉E先生。他不忍心去做；这太刻薄了。

" I don't believe you'll have the heart to do it, " said Charlie incredulously as he sealed the last note.

“我不相信你会忍心这样做，”查理盖上最后一张纸条时难以置信地说。

If someone says they " don't have the heart to do (something)" they mean they don't want to say something or do something because they think it will hurt another person's feelings – it will make that other person feel bad.

如果有人说他们“不忍心去做（某事）” ，他们的意思是他们不想说某事或做某事， 因为他们认为这会伤害他人的感情——这会让对方感觉不好。