not be selfish

My sister who is one year older than me calls me selfish a lot. I’d like to think I’m not selfish, as I yell at her that I am not but I think I am. I recently looked up selfish in a dictionary although I know what it means. It comfirmed that I am indeed selfish. I try to do things for the best of my concern even though I know I should be doing things for the best of other’s concern. In situations like this I cannot think and automatically take the selfish route. I do what’s best for me. And later I am very sorry I did.