it's the thought that counts

Rav Zevin points out an interesting parallel between the opening of Parshas VaYeira and its closing.  The parsha opens with the story of Avraham's hachnasas orchim.  No detail is spared in trying to convey to us the zerizus and exemplary manner in which Avraham performed and personified the trait of chessed.  Except for one small problem: None of the guests Avraham entertained needed his chessed at all.  The angels who came to visit were not in need of food; they needed no tree to sit under to hide from the sun; they needed no water to wash.  Apparently that is all irrelevant -- it is the burning desire of Avraham to do chessed which the parsha wants to highlight, irrespective of whether the need was real or not. 

Turning to the end of the parsha, k'lapei shemaya the plan was never for Avraham to actually sacrifice Yitzchak during the akeidah, but Avraham did not know that.  "Vayikach es ha'ma'acheles..."  The Kotzker explains that when it came to doing mitzvos, Avraham's limbs acted of their own accord (the Midrash elsewhere tells us that David haMelech's feet carried him to the Beis Medrsah each morning even if he thought to go elsewhere).  When it came time for the akeidah, since there really was no mitzvah to be done, Avraham's limbs did not react -- he had to push them to respond.  And he did so -- because in his mind he was carrying out the ratzon Hashem and nothing would stop him.  Again, the reality of whether Yitzchak was to be a korban is irrelevant, as the test Avraham faced was a measure of his ratzon and desire. 

Whether our best intentions actually get translated into action and reality is more often than not not in our hands (if I recall correctly, R' Tzadok suggests that bechira is limited to the act of deciding; whether something gets accomplished is b'ydei shamayim).  Nonetheless, the thought and desire to do good is perhaps even more important.