Theory of Self Image

Ok so I've been pondering this for a couple days now off and on. When you look down at yourself, see your body, legs, arms, etc and you think to yourself, "so this is how I look to others, man I'm scrawny" or beefy or whatever you say to yourself. personally, I think I look scrawny. But then I look in a mirror, and I see a more beefy body, more astute look, a more confident person, and I wonder, which is it that other people see when they see me? do they see the scrawny self or the more confident one? Or is my own self viewing backwards, and I'm hallucinating? So I wonder, do other people have the same occurance? where they see a different person in the mirror than they do in life? And I think more, if the mirror is right, that should be a way to boost self confidence, or is it wrong to try to boost yourself by seeing a possibly incorrect viewing, which would create a false confidence? Why is it, that even though someone can look in a mirror and see a good strong, confident self, they can't admit thats what they are? What causes these inefficiencies in us all? Anyways, thought I'd mention it.