Most people don't realize the extent of self-sacrifice, both physical (financial, health, time, worry, etc.) & spiritual (e.g. their own learning, marriage, children) that rabbis, community leaders & general volunteers lose by serving their students & community. Rabbi's children especially suffer, resenting the high expectations from a very young age! Inevitably, some even rebel against religion or communal service, either consciously or sub-consciously holding "them" responsible for their lost time with their parent. Some rebel to gain their parent's attention. Rav Kook deals with these painful phenomena of literal Mesirut Nefesh (not just Mesirut "Guf"!) & the limits involved, explaining the importance of serving Am Yisrael= serving G-d.
We find various rabbis in rabbinic literature who built their spirituality through fasting and depriving themselves of physical pleasure. Rav Kook explains that this is like "shock treatment" or bitter medicine, which healthy people don't need. In Torat Eretz Yisrael, the Living Torah most applicable to the modern world, the approach of unity is to reveal the harmony between the physical and spiritual worlds. In Israel, where even the physical is spiritual and the atmosphere is Jewish, it's much more conducive to living a life of modern orthodoxy without the dangers of losing our proportions, priorities or getting influenced by western society. Accordingly Rav Kook explains the machloket between Rava & Abaye in Masechet Shabbat.
As opposed to other types of nationalism/patriotism, which are relatively external, shallow and sometimes even racist, the Religious Zionism of Rav Kook plays an essential universal role in the moral maturation of humanity. Avraham Avinu was told to leave his land and set up a "Great Nation" in Israel who's goal is, even today & forever, to spread monotheism & morality and influence mankind. Am Yisrael as a nation, with a moral and idealistic state, economy, army & culture, plays a universal role. Rav Kook reveals his ingenious connection between monotheism & morality, & convincingly proves rationally how the Biblical "Light to the Nations" is coming true. He explains the central role of utilizing Jewish creativity for cultural influence.