Towards the beginning of Parashat Toldot, we learn of Esav's surrendering of the birthright to his younger brother, Yaakov. Rashi (25:32) explains that Esav relinquished the birthright out of genuine fear of the immense responsibility involved. Upon hearing of the many strictures, rigorous guidelines and prohibitions applicable to the service in the Bet Hamikdash (which was to be the exclusive right of the first-born), and the death penalty issued against violators, Esav declined the privilege of the birthright.
If this fear indeed formed the basis of Esav's decision to forego this privilege, then we have trouble understanding the Torah's apparent criticism of Esav in this affair: "and Esav scorned the birthright" (25:34). How did Esav's sale of his birthright reflect any sense of contempt for the service in the Mikdash? To the contrary, he was motivated by a genuine, self-effacing realization of his inadequacy and the potentially disastrous consequences of his shortcomings.
Rav Moshe Feinstein answers that Esav's intimidation did, in fact, indicate an inappropriate attitude towards the privilege of the Temple service. There are reasons for one to decline a position of leadership, authority, or honor. Unwillingness to accept the responsibility - no matter how great it may be - is not a valid reason. When presented with an opportunity, one must respond with enthusiastic preparedness to take on challenges and do what it takes to get the job done. Esav's "scorn" of the birthright involved his lackadaisical attitude in this regard. True, he was afraid; but if the birthright meant anything to him, he would have undertaken the challenge, no questions asked.
Opportunities of all kinds present themselves before us regularly. One must always weigh the difficulty involved against the potential benefit to others. Rav Moshe applied this principle to the specific instance of potential rabbis and religious teachers who shy away, inhibited by the immense responsibility that leadership positions entail. Rav Moshe urges them to reconsider and accept the challenge rather than escape it. But this lesson may be applied to each individual, regardless of professional aspirations or inclinations. One can achieve greatness only by accepting upon himself difficult challenges and setting for himself high goals. Anything less amounts to a "scornful" attitude towards the many responsibilities we have the privilege to undertake.