Altruism- What makes me do the things I do?

Altruism by definition: Unselfish concern for the welfare of others

Or, unselfish regard for or devotion to the welfare of others

and with regards to animals (zoology) :

"behavior by an animal that is not beneficial to or may be harmful to itself but that benefits others of its species"

Often, people with lots of money, usually in their latter years become philanthropists- people who perform charitable acts- selfless acts with their money. An argument could be said that they gain something from these acts- they may get some tax "write-offs", and of course they have every right to feel good about doing something positive with their money.

My question is this- what happens when a person feels the need- or instinctually feels they should perform these "random acts of kindness", or continually puts the needs of others above their own needs? What happens if this person has very little to offer? Can someone make a difference in the lives of others without money? How can this be an "instinct"? In animals it has been shown- especially in bees- that the worker/ drone bees will do everything in their power to make sure the hive and queen prosper. Their lives can willingly be lost in an effort for the rest to live. Can people have the same instincts???

Certainly most people know of Mother Teresa. Mother Teresa is known as a Catholic who continually worked to help others.

I am in no way comparing myself to Mother Teresa. I have done little to really make a differecne in the lives of others- but I do feel a strong calling to put the needs of others before mine. Is this wrong? How, when some people are so self-absorbed and selfish can the opposite seem to be the right thing to do?

I have more questions than answers in this posting- and I think have raised some interesting points- I would LOVE to hear comments from others. Do you know anyone who seems to be altruistic? Can the instinct to give of oneself override the self-preservation instinct?