They just found it impossible to imagine anyone going to the immense effort required.

It took immense effort merely to move his lips and form words.

It required an immense effort of will to bring his emotions under control.

Then, with an immense effort, she got her chin up again.

No one knows why the trees make this immense effort when they get nothing evident in return.

As if with an immense effort he pushed himself to his feel?

Keeping his voice level with immense effort, he told them.

And then there was that immense effort to get his team over the line on Sunday.

With immense effort, I brought my eyes to focus on him.

With an immense effort of will, he kept his voice low; still, it was harsh.