I had to learn to not let people take so much of me that they left me empty. But I cared so much that I couldn't see it. I had to learn the hard way when I finally realized a close friend was using me for her own gain and giving nothing back. Give, care, but dont let others take you for granted or use you. Sometimes we have to put ourselves first for our own physical and mental health.
But therein lies the problem, you can't expect others to do as you would... this is something my girls deal with. My hubby and I will do anthing for our girls and so they think others will too. They are always there for their friends no matter what. Many times they are let down by others. Hard to know because many people are not themselves when you first meet them so how to know who is real and who is only there for what they can take?