Selfless or Selfish

How can someone who is described by everyone around as selfless then describe themselves as selfish? Of course there are so many differences between these two words. One thing I don't understand is how someone can be both. I guess,I think it all depends on perception of the situation at hand. For example, I know that if I were to do things for someone and I don't directly benefit from it, it would seem selfless. But, on the other hand if I thought that I was gaining something, that I like helping people, I could see my self as selfish. I do like to help people but I never see it as a selfish act. I mean, this is making me think of the quote that one of my friends used to say, "50% of the people don't care about your problems, and the other 50% just listen so they feel better about their own lives." I mean, I have never directly said that it makes me feel better about my life, but, I guess in a weird way it would but it's not a direct reaction. So I think that I don't try to help people for selfish act, but, it could appear to someone to be that way depending on how the perceive the entire situation.