Any further effort to do so would be a waste of time and energy.
Everything else seems like a waste of time and energy.
His father considered talking a waste of energy, he said.
It is a waste of life and energy, nothing more.
You told me it was a waste of my time and energy.
At any rate, it seems to me a waste of energy to try to learn what is beyond my understanding.
It was a waste of energy, but they didn't know that yet.
Until then, it was a waste of mental energy to try to second guess what would happen.
Ah, can you not see that it is a waste of time and energy?
Proving who did it would be difficult and a waste of energy.