Well, there is a fine line between being selfish and self preservation. It's kind of like the difference between giving love and receiving love. Love is only perfect, when it's both giving and receiving. The answer to your question lies between giving and receiving. We are built to give and receive. We eat, we digest and we eliminate.(tried not to be graphic; we give or let go) The Dead Sea is always receiving and never giving and that's why it's dead. Sometimes having your needs met is tied up in meeting the needs of others.
Another way of looking at it is, for example love, if you do not love yourself you can not love anyone else. My sister always says, "Fill yourself up with the love first and love will increase around you."
Either way, balance is the answer. He you will find that balance, when you are governed by Love.