When you're on a plane, the safety mesures mention that before you try to help the person next to you, please secure your own mask beforehand, and then help the people around you. The same logic applies to life.
You cannot invest your fuel, your spiritual and emotional and physical energy into others if you haven't allowed yourself to it. You're more worthy of yourself than anybody is. Nurture it, care for it, help it, listen to it. It needs you as much as you need it. Only then, will you be in shape to properly be there for the people you care about. People can offer you small tools, bonuses. And that's it. You're the only person that help you. Others just help enable the process. The war of believing how worthy you are of yourself.