"The glory of God is man fully alive." -St. Irenaeus
This is an oft-quoted statement from one of the early Church fathers, but I wonder how many people have thought about what it fully means. I would think that all of us, whether religious or not, would want to live our lives "fully alive." To be fully alive, I think it naturally follows that we must be fully human, because that is what we are. A tree cannot be fully alive by trying to be a flower, or a mountain, or a butterfly (indulge me in my anthropomorphizing). Man cannot be fully alive unless he is fully man (or woman).
Blessed John Paul the Great, before he was pope, was a great philosopher and spent much time and energy developing an anthropology that drew from ancient Greece to Jesus to modern day. In Gaudium et Spes, which he had a large part in writing, we learn that “Man is the only creature on earth which God willed for
itself, [and he] cannot fully find himself except through a sincere gift of himself.” (GS 24) I don't have the knowledge or ability to defend that statement as it deserves, but I do know that my own experience has shown this to be true. JPII also said that "to be human means to be called to interpersonal communion." If you take it from a religious perspective, it makes sense that, created in the image of the Trinitarian communion, we would only find fulfillment in relationship with others and God. From a biologic, psychologic, philosophical perspective, we are the only beings capable of conscious thought, with a will and an intellect, able to experience love. Man does not make sense in isolation, only in communion.
So we can see that man, "fully alive", must be in relationship, and that relationship can not be one of selfishness and utilitarianism. Communion can only be achieved through self-gift and a receiving of that gift. So much of today's world facilitates relationships that give me something, that I profit from, and that allow me to rise in the standards of the world--wealth, beauty, power--which, as you'll notice, are not what it means to be "fully alive."
It's counter-intuitive only because there are so few voices for truth, and the voices of the world are so loud. If you stop to really think about it, it's completely intuitive. It's a challenge that I continue to take upon myself to live in a way that will help me become the best version of myself, the most fully-alive version of myself. Which is to say the version that gives of myself, is in communion with others and with the God who created me in His image.