The Ramban, in his introduction to the story of Akeidos Yitzchok (Bereishis 22:1), explains the purpose of a nisoyon. A person is tested for his own benefit: so that he can be rewarded for a good deed and not merely a good heart. Although Avraham Avinu succeeded in purifying his heart to the nth degree, nevertheless this greatness remained merely potential (b'koach). The ten nisyonos with which Avraham was tested, were a means of turning his greatness from potential into concrete actions (b'po'el), because the ultimate objective is perfecting one's actions.
Rav Wolbe (Ma'amerei Yemei Ratzon pg. 97) writes, with this in mind let us try to understand the Mishna in Pirkei Avos (2, 13). R' Yochanan ben Zakkai asks his disciples to, "Seek out the proper path to which a man should cling." They returned with various answers: a good eye, a good friend, a good neighbor, one who considers the outcome of his deeds and a good heart. Said R' Yochanan ben Zakkai, "I prefer the words of R' Elazar (who chose a good heart), for your words are included in his words."
The other four responses all focused on tangible actions and a practical way of life (b'po'el). A good eye rids one of much evil. He judges others favorably and he is cleansed from hatred and jealousy. A good friend will perform kindness, share in another's grief, forgive and forget and many other positive middos. A good neighbor surpasses a good friend, for he contains all those qualities and, moreover, he acts beneficially to even those who are not his closest confidantes. Someone who considers the outcome of his actions fears Hashem, and his every action is made with an acute awareness of its ramifications. If so, in what aspect does a good heart, which represents potential (b'koach), supersede all these other positive qualities?
Rav Wolbe explains that a good heart is the best preparation for life, because it encompasses all good actions. The actions are the most important aspect of one's avodah, and they properly portray the goodness of the heart of one who is performing those actions. A lack of an ability to perform reflects a flaw in the "goodness" of the heart. He who truly possesses a good heart will in time come to be a person who possesses a good eye, is a good friend and neighbor, and one who considers the consequences of his deeds. Because Avraham possessed a good heart, he had the ability to pass all ten nisyonos with which he was tested.
Rosh Hashana is the day on which we are supposed to accept upon ourselves the yoke of Heavenly Kingship. Accepting this yoke is akin to possessing the good heart mentioned in the Mishna; it is a general concept that encompasses all aspects of our lives. However, just like a good heart, accepting the yoke of Heaven cannot remain only b'koach - it must translate into actions. We must make an effort to focus on Hashem's loftiness, His Kingship and the great advantage gained by accepting this yoke upon oneself. However, it can't end there. This knowledge must translate into actions, and the b'po'el of accepting the yoke of Heaven fine tunes our middos to act solely in accordance with the will of Hashem.
We should not try to be someone we are not. In each person's specific situation - with his friends and family, his house and necessities - he must make an effort to act in accordance with the will of Hashem. Our actions after Rosh Hashana will mirror the extent to which we accepted the yoke of Hashem on Rosh Hashana!
May we all merit a Kesiva V'Chasima Tova!