The Tanya repeatedly mentions that we learn from the words סור מרע, stay away from evil, the obligation to fear Hashem. This fear is expressed by the non-violation of the 365 negative commandments. The other half of the Pasuk, עשה טוב, do good, represents the commandment to love Hashem which is manifest by the observance of the 248 positive commandments. The Tanya goes on to say that if one observes the Mitzvot with an awareness of love and fear of Hashem, he will attach himself to higher and higher levels of holiness. The Tanya warns against the Jew whose worship of Hashem is only love without fear. Such an individual will tend to feel that there is no need to worry about violating the negative commandments of the Torah. Therefore, one must always contemplate Hashem's greatness, in order for his observance of the Mitzvot be a combination of love and fear of Hashem.