brak wysiłku

It was not for lack of effort on his part.

This has nothing to do with any lack of effort.

But this failure is not for a lack of effort.

The reason has nothing to do with a lack of effort.

If she didn't, it probably wouldn't be from lack of effort.

The poor grade has not come from lack of effort.

She was surprised by the lack of effort it took him.

At least we know it didn't fall through lack of effort.

I'm certainly going to try to win every week, and believe me, it's not from a lack of effort.

Our teachers' chief concern with your son's school work is his lack of effort.