When you feel you cannot continue in your position for another minute, and all that is in human power has been done, that is the moment when the enemy is most exhausted, and when one step forward will give you the fruits of the struggle you have borne
I've learned, I think, to be able to distinguish between the necessary and the unnecessary as far as my limited outside time is concerned. Saying 'no' politely is a necessity if one wants to lead any kind of stable life.