There are two mitzvos in Parshas Kedoshim that together encompass the entirety of our avodas Hashem. The first is "kedoshim tihiyu- You should be holy", which is interpreted differently by Rashi and Ramban. Rashi explains this passuk to refer specifically to prohibited relationships. The Rambam expands its scope and includes it in Sefer Kedusha of Mishna Torah in the halachos of kashrus as well. According to these rishonim, it is the scrupulous observance of these intricate laws that makes up a life of kedusha.
Ramban interprets kedoshim tihiyu as referring to one's lifestyle, and understands it to proscribe all physical indulgences that, although not specifically prohibited, do not fit in to a lifestyle of kedusha. Thus, according to Ramban, even if all the detailed laws of Sefer Kedusha are observed, a gluttonous, hedonistic lifestyle is a violation of kedoshim tihiyu, since being kadosh demands a lifestyle of kedusha.
Both interpretations of kedoshim tihiyu focus on our relationship with Hashem. The second expansive mitzva of Parshas Kedoshim is "V'ahavta l'reacha kamocha - You should love your fellow man as you love yourself", which includes all aspects of bein adam la'chaveiro. The Baal Halachos Gedolos counts different examples of chessed, such as bikur cholim, nichum aveilim, etc. as separate mitzvos. In Rambam's count of the mitzvos, however, he includes all mitzvos of chessed in one mitzvah, i.e. subsumed under the mitzva of "V'ahavta l'reacha kamocha". According to Rambam, why don't distinct types of chessed count as separate mitzvos?
There are two dimensions to the mitzvos bein adam la'chaveiro. The Chafetz Chaim comments on the passuk in the navi Micha that Hashem requires us to, "asos mishpat v'a'havas chessed - act justly and love kindness." Why is it that with respect to justice we are told to act, while regarding kindness we are told to love kindness as well? The Chafetz Chaim explains that justice can be served through action alone. Kindness, however, can't be fully implemented if one remains an unkind person internally; in order to act truly kindly, we must become individuals who love performing acts of kindness. If the Torah would have commanded us concerning specific acts of chessed, we may have misunderstood that kind acts alone suffice. Therefore this mitzva is formulated using the word "love" because we must become loving people.
Feeling love is essential, but it is not enough. There is an additional source which obligates us in each of the numerous specific acts of chessed: the Torah delineates the different acts of kindness Hashem performs, and we are required to emulate Hashem. Just as He visits the sick, comforts the bereaved, and rejoices with the chosson and kallah, so too must we follow suit. The Torah illustrates how Hashem is involved in the specifics to teach us that just having a good heart and vague feelings of love are not sufficient, rather these emotions must result in concrete actions to our fellow man.
These two principles upon which the entire Torah rests, kedusha and ahava, have both broad and narrow applications. We must perfect our actions as well as our perspective on how we relate to the physical world that surrounds us. Similarly, we must excel in our practical acts of kindness while simultaneously becoming loving sensitive individuals. As we read the myriad mitzvos, both bein adam la'makom and bein adam la'chaveiro found in Parshas Kedoshim, let us focus on the dual goals of both facets of Torah observance.