Inner-rage where does it come from?

I am ordinarily not an angry person; however, there times I become enraged and not sure why. Sometimes the stupidest things will trigger this and I become enraged for reasons that other people would laugh over. I normally have an extremely long fuse but when I explode, look out. However, every once in awhile I find myself exploding without warning. I hate when I feel the rage welling up inside of me. My family sometimes triggers this but sometimes it's something I see on TV and read somewhere. I mean I have control over it and I'm not picking people off that go by my house. I just wish I never felt it. However, a person gets tired of being walked on. I guess I'm tired of being people's doormat.