My kids. When things get real dark, all I have to do is remind myself that there are three little creatures that (for now) love me unconditionally and rely on me to keep them alive and well-adjusted from day to day. Has a way of keeping me from falling off the edge. And in another sense: when daily life starts to feel too hectic, and the stresses of giving my life so completely to other people all the time start to bear down, all I have to do is remind myself that my kids are happy and healthy, and although they push my blood pressure into the red sometimes, I've seen the alternative to good health and total stability, and I couldn't imagine a life without any one of them. I'd rather be stressed with them here than less stressed with one less kid.
I suspect thenewgreen would agree with you wholeheartedly.