For as long as you could remember you've put everybody and everything else before taking care of yourself. There are a million things on your list of priorities that are above making sure your needs are met. You give and give and give to others until you feel a pit of emptiness so deep inside that you can't seem to fill it no matter how hard you try.
You work tirelessly to make temporary people happy, but what about your happiness? You have no idea what makes your happy, because you haven't taken even 5 seconds to stop and think about it. Seeing others happy brings you joy, but what about when those people are no longer around? You're left with no feeling whatsoever, just a numbness that hits deep in your core. That's what happens when you allow others to be your happiness? You're directionless without another person. But that's no way to live, because finding joy in your own soul is the most secure feeling in the world. It's something that not one person on this planet can take away from you.
To find satisfaction within, you have to learn how to take care of yourself without feeling selfish. How do you rationalize this after spending years and years of believing that if your focus was on yourself, then by default you were neglecting others? This couldn't be further from the truth. In fact, in order to properly take care of other people in a healthy way, you must take care of yourself first. Repeat this to yourself when you're experiencing feelings of guilt: you don't need to tear yourself apart in order to make others feel whole. Feeling fulfilled and complete is something that each person must do for themselves.
Each piece of your heart and soul that you give away to someone will be only a temporary fix for that person. Not to mention, it's not your responsibility to "fix" anybody but yourself. While being generous to a fault can make you feel that way, allowing other people to work out their issues while you focus on yourself does not make you a bad person. It doesn't make you self-centered, it just means that you've come to realize that people who drain the happiness out of others to try and make themselves feel whole are not healthy individuals.
Turning your focus onto figuring out what makes life wholesome and worthwhile is a vital first step in putting yourself first. Grasping onto what the people around you like and pretending you enjoy the same things is a practice that you've perfected throughout the years. All in an effort to feel like you belong somewhere. But when you truly find what makes your heart soar, you won't need a single other person to feel complete. That's when you can truly care for yourself, and in turn, for others.