Each of us has a different capacity to give to others without losing ourselves. Some of us can give only a bit, some of us give so much there is nothing of us left. Your real job, not necessarily the one you get paid for, is to find the opportunity to infuse meaning into your life by challenging yourself to give in a way that jeopardizes your happiness.
Look around for where you can make a big difference. It is likely a place that will shake you up.