Turning another year older is a privilege; each year we learn from our experiences and cultivate more awareness about ourselves and the world around us. It's beautiful, but can also be heartbreaking, if we're gunna get real with it.
I remember being 15 and thinking, this is the person I am and will be forever. I remember being 18 and thinking the same thing; I remember being 20 living in Paris thinking the same thing; I remember getting married at 27 and thinking the same thing.
However, the reality is that we are ever-changing and not fixed. We are constantly molded by our experiences, whether they be day-to-day events or rock-you-senseless-to-your-core moments. Feelings and goals and passions and thoughts can change on a daily basis...
Thus, living authentically is living in the present moment. It's honoring your being, your soul, in each present moment, without judgment. It's allowing yourself (with respect to others) to be yourself.
It cannot be influenced by others; I'm a romantic existentialist, and I believe we are inevitably alone - as they say, we are born alone and we die alone. Our experience is only our own, therefore our authentic selves can only be shaped by ourselves and our perceived experience, not by anyone or anything else.
Make the time to take a moment to be present, to breathe deeply and engage your five senses and come into that sweet present moment. Immerse yourself in the "this is it," without expectation or searching for meaning.