Sometimes it is not enough to do your best. Sometimes you have to do what is required.
My good friend and colleague, Richard Hart, has this phrase posted in his classroom, and I have heard him repeat it often over the years, to his young welding students, in his booming bass voice.
It is often too easy for any of us to excuse our half-assed attempts at a task, by using the pat "Well, I did my best." As teachers we often tell our students, "Just do your best."
The problem with doing our best, is that often we underestimate ourselves, we fail to raise our own bar, and sometimes our best doesn't cut it. Sometimes we need to do what is required, even if we need to push ourselves that much harder.