Effect of other people

This is a very uncharacteristic blog of mine. Usually i have sth in mind before i begin to write; some vague idea, or some even in my life, or some random topic i want to write about.

Well, I'm not totally blank... i am thinking, and i am not finding an answer.

Why is it that some people make me feel good about myself, while some not.
Why presence of some makes me remain calm wrt most haunting issues in my life, and others make me panic.
Why some make me feel i am worth more, while amongst others i feel I'm worth crap.
Why do i feel negative with some, and positive with others?

I know that all this is idiotic thought, but the effects i have talked about above are very much real.

Why does this happen? I don't know. Is it them, or is it me somewhere, somehow.
It would be good to have some answer.
As of now, i don't have a clue.