I'm very self absorbed and can't stop thinking about myself?

It's like a disease. All day long all I think about is my personality, my characteristics, my place in life, the way I look, how people think of me, I go so far as to imagine my friends having conversations about me. I love people, honestly, and I try to help people as much as I can. But sometimes I do something good and all I think about is how good others will see me now. Please help me, I'm sick of it.