defensive

when are you suppose to get defensive? why do we always have to get our point across. well I always get people telling me I'm very defensive even my coworker and my family said they will not approach me about a situation because every time they do I don't really hear them out because I always want to get my point across where I ignored what their telling me. I noticed that about me a few time if you approach me some time away  I will do the same to you, but that's not the way to go about things in life. Sometime even with my character people tell me you have a serious face where I was afraid to approach you, I just don't understand why do most people judge someone by character. I'm really trying to stop being so defensive and actually listen to someone before I jump to conclusion.