“Just do your best," Mom said. "You can't do any better than your best.”
“Do your best, and be a little better than you are.”
“The world needs you more than you can think of! Do your best to make this place better.”
“Doing your best is more important than being your best.”
“I come to the office each morning and stay for long hours doing what has to be done to the best of my ability. And when you've done the best you can, you can't do any better.”
“If you can't do, you had best shut up. He started to slam the door, thought better of it. If you can't do, you'd best not slam doors.”