Each person must define for themself what is their best at any given moment in time. The only person that can stop them from doing their best is themself. When we do not put forth our best effort we hurt not only ourself, our conception of what we are capable of, but also those who depend upon us. If a task is worth doing and we do not do it to the best of our current ability, then we short change ourself and we lower our own estimation of what we can do each following day. By doing our best we set up an upward spiral of achievements. When we do less that our best we set up a downward spiral of achievement. When we say we can - we can. When we say we cannot -- we cannot. When I look in the mirror -- I want to see a person who did their best with each opportunity. I can be happy and at peace with myself.