There is a well known Gemara (Rosh Hashana 16b) that describes the judicial scene in Heaven on Rosh Hashana. "There are three books open: Those who are completely righteous are immediately signed and sealed for life. Those who are completely wicked are immediately signed and sealed for death and those in the middle (beinonim) hang in balance until Yom Kippur. If they are found to have merit they are sealed for life, and if they lack merit they are sealed for death." The simple explanation is that the righteous refer to those with more mitzvos than aveiros, the wicked are those with more aveiros than mitzvos and the beinonim are those whose portfolio contains half mitzvos and half aveiros. However, the Alter of Kelm asks that Chazal say that one who does not fulfill even one Rabbinic commandment is considered a rasha - one who is wicked. If so, how can we refer to such a person as righteous simply because his merits outweigh his transgressions? He explains that the criterion for defining one as a tzaddik in the context of Rosh Hashana is not the amount of mitzvos he has performed. Rather, one is considered a tzaddik if he is close to doing teshuva, while a rasha is one who is far from doing teshuva.
If so, asks Rav Wolbe (Ma'amerei Yemei Ratzon pg. 228), who can be considered a beinoni, since a person is either close to the performance of teshuva or far from this process? He answers by way of clarifying a stanza in the selicha said on Erev Rosh Hashana (28). "Man serves two masters throughout his life: He serves his yetzer hara and his Creator as he wills. It is good for him to cleave to his Creator at all times for then he is a servant [of Hashem] and free from his master (yetzer hara)." A person mightserve Hashem through davening, learning Torah or any other mitzvah, and nevertheless, still desire to enjoy life the way he deems fit. Outside the framework of his spiritual servitude to Hashem, he wishes to behave among his friends as he pleases, without being inhibited by thoughts of yiras shamayim. Who doesn't feel this dichotomy to a certain extent?
The person described above might feel pangs of regret at his shortcomings in the spiritual realm. He realizes that his tefillos are lacking concentration and he has fallen short in his performance of mitzvos. With regard to this aspect he can be considered, "One close to performing teshuva." In contrast, he perceives his second "identity" - the half that wishes to live as he pleases - as a completely different entity. He has no feelings of guilt despite his shortcomings and transgressions in this area, and in this regard he cannot be considered, "Close to performing teshuva." Such a person is the "beinoni" mentioned in the Gemara Rosh Hashana.
So what is the avodah of a beinoni? He must make an effort to internalize the advice of the selicha. "It is good for him to cleave to his Creator at all times - for then he is a servant [of Hashem] and free from his master (yetzer hara)." The intention is not that one must become completely righteous overnight - for that is unrealistic and cannot endure. However, he should take some time to contemplate his purpose here on Earth and adjust his mindset accordingly.
G'mar Chasima Tova!